[PATCH v5 01/20] drm/nouveau/kms: Fix some indenting in nouveau_dp_detect()

[PATCH v5 01/20] drm/nouveau/kms: Fix some indenting in nouveau_dp_detect()

[Lyude Paul]

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 8a0f7994e1aeb..ee778ddc95fae 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -76,10 +76,10 @@ nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
 	nv_encoder->dp.link_nr = dpcd[2] & DP_MAX_LANE_COUNT_MASK;
 
 	NV_DEBUG(drm, "display: %dx%d dpcd 0x%02x\n",
-		     nv_encoder->dp.link_nr, nv_encoder->dp.link_bw, dpcd[0]);
+		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw, dpcd[0]);
 	NV_DEBUG(drm, "encoder: %dx%d\n",
-		     nv_encoder->dcb->dpconf.link_nr,
-		     nv_encoder->dcb->dpconf.link_bw);
+		 nv_encoder->dcb->dpconf.link_nr,
+		 nv_encoder->dcb->dpconf.link_bw);
 
 	if (nv_encoder->dcb->dpconf.link_nr < nv_encoder->dp.link_nr)
 		nv_encoder->dp.link_nr = nv_encoder->dcb->dpconf.link_nr;
@@ -87,7 +87,7 @@ nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
 		nv_encoder->dp.link_bw = nv_encoder->dcb->dpconf.link_bw;
 
 	NV_DEBUG(drm, "maximum: %dx%d\n",
-		     nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
+		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
 
 	nouveau_dp_probe_oui(dev, aux, dpcd);
 
-- 
2.26.2

[PATCH v5 02/20] drm/nouveau/kms/nv50-: Remove open-coded drm_dp_read_desc()

[Lyude Paul]

Noticed this while going through our DP code - we use an open-coded
version of drm_dp_read_desc() instead of just using the helper, so
change that. This will also let us use quirks in the future if we end up
needing them.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c |  3 ++-
 drivers/gpu/drm/nouveau/nouveau_dp.c        | 30 +++++++--------------
 drivers/gpu/drm/nouveau/nouveau_encoder.h   |  4 ++-
 3 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 7674025a4bfe8..e12957e6faa7c 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -435,7 +435,8 @@ nouveau_connector_ddc_detect(struct drm_connector *connector)
 
 		switch (nv_encoder->dcb->type) {
 		case DCB_OUTPUT_DP:
-			ret = nouveau_dp_detect(nv_encoder);
+			ret = nouveau_dp_detect(nouveau_connector(connector),
+						nv_encoder);
 			if (ret == NOUVEAU_DP_MST)
 				return NULL;
 			else if (ret == NOUVEAU_DP_SST)
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index ee778ddc95fae..c4e9c21d4dd2b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -36,27 +36,9 @@ MODULE_PARM_DESC(mst, "Enable DisplayPort multi-stream (default: enabled)");
 static int nouveau_mst = 1;
 module_param_named(mst, nouveau_mst, int, 0400);
 
-static void
-nouveau_dp_probe_oui(struct drm_device *dev, struct nvkm_i2c_aux *aux, u8 *dpcd)
-{
-	struct nouveau_drm *drm = nouveau_drm(dev);
-	u8 buf[3];
-
-	if (!(dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_OUI_SUPPORT))
-		return;
-
-	if (!nvkm_rdaux(aux, DP_SINK_OUI, buf, 3))
-		NV_DEBUG(drm, "Sink OUI: %02hx%02hx%02hx\n",
-			     buf[0], buf[1], buf[2]);
-
-	if (!nvkm_rdaux(aux, DP_BRANCH_OUI, buf, 3))
-		NV_DEBUG(drm, "Branch OUI: %02hx%02hx%02hx\n",
-			     buf[0], buf[1], buf[2]);
-
-}
-
 int
-nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
+nouveau_dp_detect(struct nouveau_connector *nv_connector,
+		  struct nouveau_encoder *nv_encoder)
 {
 	struct drm_device *dev = nv_encoder->base.base.dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
@@ -89,7 +71,13 @@ nouveau_dp_detect(struct nouveau_encoder *nv_encoder)
 	NV_DEBUG(drm, "maximum: %dx%d\n",
 		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
 
-	nouveau_dp_probe_oui(dev, aux, dpcd);
+	ret = drm_dp_read_desc(&nv_connector->aux, &nv_encoder->dp.desc,
+			       drm_dp_is_branch(dpcd));
+	if (ret) {
+		NV_ERROR(drm, "Failed to read DP descriptor on %s: %d\n",
+			 nv_connector->base.name, ret);
+		return ret;
+	}
 
 	ret = nv50_mstm_detect(nv_encoder->dp.mstm, dpcd, nouveau_mst);
 	if (ret == 1)
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index a72c412ac8b14..6424cdcb4913f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -33,6 +33,7 @@
 #include <drm/drm_dp_mst_helper.h>
 #include "dispnv04/disp.h"
 struct nv50_head_atom;
+struct nouveau_connector;
 
 #define NV_DPMS_CLEARED 0x80
 
@@ -64,6 +65,7 @@ struct nouveau_encoder {
 			struct nv50_mstm *mstm;
 			int link_nr;
 			int link_bw;
+			struct drm_dp_desc desc;
 		} dp;
 	};
 
@@ -104,7 +106,7 @@ enum nouveau_dp_status {
 	NOUVEAU_DP_MST,
 };
 
-int nouveau_dp_detect(struct nouveau_encoder *);
+int nouveau_dp_detect(struct nouveau_connector *, struct nouveau_encoder *);
 enum drm_mode_status nv50_dp_mode_valid(struct drm_connector *,
 					struct nouveau_encoder *,
 					const struct drm_display_mode *,
-- 
2.26.2

[PATCH v5 03/20] drm/nouveau/kms/nv50-: Just use drm_dp_dpcd_read() in nouveau_dp.c

[Lyude Paul]

Since this actually logs accesses, we should probably always be using
this imho…

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index c4e9c21d4dd2b..8db9216d52c69 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -42,16 +42,12 @@ nouveau_dp_detect(struct nouveau_connector *nv_connector,
 {
 	struct drm_device *dev = nv_encoder->base.base.dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
-	struct nvkm_i2c_aux *aux;
-	u8 dpcd[8];
+	struct drm_dp_aux *aux = &nv_connector->aux;
+	u8 dpcd[DP_RECEIVER_CAP_SIZE];
 	int ret;
 
-	aux = nv_encoder->aux;
-	if (!aux)
-		return -ENODEV;
-
-	ret = nvkm_rdaux(aux, DP_DPCD_REV, dpcd, sizeof(dpcd));
-	if (ret)
+	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
+	if (ret != sizeof(dpcd))
 		return ret;
 
 	nv_encoder->dp.link_bw = 27000 * dpcd[1];
-- 
2.26.2

[PATCH v5 04/20] drm/nouveau/kms/nv50-: Use macros for DP registers in nouveau_dp.c

[Lyude Paul]

No functional changes.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 8db9216d52c69..4030806e3522b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -50,11 +50,13 @@ nouveau_dp_detect(struct nouveau_connector *nv_connector,
 	if (ret != sizeof(dpcd))
 		return ret;
 
-	nv_encoder->dp.link_bw = 27000 * dpcd[1];
-	nv_encoder->dp.link_nr = dpcd[2] & DP_MAX_LANE_COUNT_MASK;
+	nv_encoder->dp.link_bw = 27000 * dpcd[DP_MAX_LINK_RATE];
+	nv_encoder->dp.link_nr =
+		dpcd[DP_MAX_LANE_COUNT] & DP_MAX_LANE_COUNT_MASK;
 
 	NV_DEBUG(drm, "display: %dx%d dpcd 0x%02x\n",
-		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw, dpcd[0]);
+		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw,
+		 dpcd[DP_DPCD_REV]);
 	NV_DEBUG(drm, "encoder: %dx%d\n",
 		 nv_encoder->dcb->dpconf.link_nr,
 		 nv_encoder->dcb->dpconf.link_bw);
-- 
2.26.2

[PATCH v5 05/20] drm/nouveau/kms: Don't clear DP_MST_CTRL DPCD in nv50_mstm_new()

[Lyude Paul]

Since fa3cdf8d0b09 ("drm/nouveau: Reset MST branching unit before
enabling") we've been clearing DP_MST_CTRL before we start enabling MST.
Since then clearing DP_MST_CTRL in nv50_mstm_new() has been unnecessary
and redundant, so let's remove it.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index e7874877da858..c4d138f0ca054 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1535,17 +1535,6 @@ nv50_mstm_new(struct nouveau_encoder *outp, struct drm_dp_aux *aux, int aux_max,
 	struct drm_device *dev = outp->base.base.dev;
 	struct nv50_mstm *mstm;
 	int ret;
-	u8 dpcd;
-
-	/* This is a workaround for some monitors not functioning
-	 * correctly in MST mode on initial module load.  I think
-	 * some bad interaction with the VBIOS may be responsible.
-	 *
-	 * A good ol' off and on again seems to work here ;)
-	 */
-	ret = drm_dp_dpcd_readb(aux, DP_DPCD_REV, &dpcd);
-	if (ret >= 0 && dpcd >= 0x12)
-		drm_dp_dpcd_writeb(aux, DP_MSTM_CTRL, 0);
 
 	if (!(mstm = *pmstm = kzalloc(sizeof(*mstm), GFP_KERNEL)))
 		return -ENOMEM;
-- 
2.26.2

[PATCH v5 06/20] drm/nouveau/kms: Search for encoders' connectors properly

[Lyude Paul]

While the way we find the associated connector for an encoder is just
fine for legacy modesetting, it's not correct for nv50+ since that uses
atomic modesetting. For reference, see the drm_encoder kdocs.

Fix this by removing nouveau_encoder_connector_get(), and replacing it
with nv04_encoder_get_connector(), nv50_outp_get_old_connector(), and
nv50_outp_get_new_connector().

v2:
* Don't line-wrap for_each_(old|new)_connector_in_state in
  nv50_outp_get_(old|new)_connector() - sravn
v3:
* Fix potential uninitialized usage of nv_connector (needs to be
  initialized to NULL at the start). Thanks kernel test robot!
v4:
* Actually fix uninitialized nv_connector usage in
  nv50_audio_component_get_eld(). The previous fix wouldn't have worked
  since we would have started out with nv_connector == NULL, but
  wouldn't clear it after a single drm_for_each_encoder() iteration.
  Thanks again Kernel bot!

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv04/dac.c      |  2 +-
 drivers/gpu/drm/nouveau/dispnv04/dfp.c      |  7 +-
 drivers/gpu/drm/nouveau/dispnv04/disp.c     | 18 +++++
 drivers/gpu/drm/nouveau/dispnv04/disp.h     |  4 +
 drivers/gpu/drm/nouveau/dispnv04/tvnv04.c   |  2 +-
 drivers/gpu/drm/nouveau/dispnv04/tvnv17.c   |  2 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c     | 88 +++++++++++++++++----
 drivers/gpu/drm/nouveau/nouveau_connector.c | 14 ----
 drivers/gpu/drm/nouveau/nouveau_encoder.h   |  6 +-
 9 files changed, 105 insertions(+), 38 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv04/dac.c b/drivers/gpu/drm/nouveau/dispnv04/dac.c
index ffdd447d87068..22d10f3285597 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/dac.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/dac.c
@@ -419,7 +419,7 @@ static void nv04_dac_commit(struct drm_encoder *encoder)
 	helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
 	NV_DEBUG(drm, "Output %s is running on CRTC %d using output %c\n",
-		 nouveau_encoder_connector_get(nv_encoder)->base.name,
+		 nv04_encoder_get_connector(nv_encoder)->base.name,
 		 nv_crtc->index, '@' + ffs(nv_encoder->dcb->or));
 }
 
diff --git a/drivers/gpu/drm/nouveau/dispnv04/dfp.c b/drivers/gpu/drm/nouveau/dispnv04/dfp.c
index f9f4482c79b54..42687ea2a4ca3 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/dfp.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/dfp.c
@@ -184,7 +184,8 @@ static bool nv04_dfp_mode_fixup(struct drm_encoder *encoder,
 				struct drm_display_mode *adjusted_mode)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
-	struct nouveau_connector *nv_connector = nouveau_encoder_connector_get(nv_encoder);
+	struct nouveau_connector *nv_connector =
+		nv04_encoder_get_connector(nv_encoder);
 
 	if (!nv_connector->native_mode ||
 	    nv_connector->scaling_mode == DRM_MODE_SCALE_NONE ||
@@ -478,7 +479,7 @@ static void nv04_dfp_commit(struct drm_encoder *encoder)
 	helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
 	NV_DEBUG(drm, "Output %s is running on CRTC %d using output %c\n",
-		 nouveau_encoder_connector_get(nv_encoder)->base.name,
+		 nv04_encoder_get_connector(nv_encoder)->base.name,
 		 nv_crtc->index, '@' + ffs(nv_encoder->dcb->or));
 }
 
@@ -591,7 +592,7 @@ static void nv04_dfp_restore(struct drm_encoder *encoder)
 
 	if (nv_encoder->dcb->type == DCB_OUTPUT_LVDS) {
 		struct nouveau_connector *connector =
-			nouveau_encoder_connector_get(nv_encoder);
+			nv04_encoder_get_connector(nv_encoder);
 
 		if (connector && connector->native_mode)
 			call_lvds_script(dev, nv_encoder->dcb, head,
diff --git a/drivers/gpu/drm/nouveau/dispnv04/disp.c b/drivers/gpu/drm/nouveau/dispnv04/disp.c
index 900ab69df7e8f..3f046b917c85c 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/disp.c
@@ -35,6 +35,24 @@
 
 #include <nvif/if0004.h>
 
+struct nouveau_connector *
+nv04_encoder_get_connector(struct nouveau_encoder *encoder)
+{
+	struct drm_device *dev = to_drm_encoder(encoder)->dev;
+	struct drm_connector *connector;
+	struct drm_connector_list_iter conn_iter;
+	struct nouveau_connector *nv_connector = NULL;
+
+	drm_connector_list_iter_begin(dev, &conn_iter);
+	drm_for_each_connector_iter(connector, &conn_iter) {
+		if (connector->encoder == to_drm_encoder(encoder))
+			nv_connector = nouveau_connector(connector);
+	}
+	drm_connector_list_iter_end(&conn_iter);
+
+	return nv_connector;
+}
+
 static void
 nv04_display_fini(struct drm_device *dev, bool suspend)
 {
diff --git a/drivers/gpu/drm/nouveau/dispnv04/disp.h b/drivers/gpu/drm/nouveau/dispnv04/disp.h
index 495d3284e8766..5ace5e906949a 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/disp.h
+++ b/drivers/gpu/drm/nouveau/dispnv04/disp.h
@@ -6,6 +6,8 @@
 
 #include "nouveau_display.h"
 
+struct nouveau_encoder;
+
 enum nv04_fp_display_regs {
 	FP_DISPLAY_END,
 	FP_TOTAL,
@@ -93,6 +95,8 @@ nv04_display(struct drm_device *dev)
 
 /* nv04_display.c */
 int nv04_display_create(struct drm_device *);
+struct nouveau_connector *
+nv04_encoder_get_connector(struct nouveau_encoder *nv_encoder);
 
 /* nv04_crtc.c */
 int nv04_crtc_create(struct drm_device *, int index);
diff --git a/drivers/gpu/drm/nouveau/dispnv04/tvnv04.c b/drivers/gpu/drm/nouveau/dispnv04/tvnv04.c
index b701a4d8fe760..3ba7b59580d59 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/tvnv04.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/tvnv04.c
@@ -172,7 +172,7 @@ static void nv04_tv_commit(struct drm_encoder *encoder)
 	helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
 	NV_DEBUG(drm, "Output %s is running on CRTC %d using output %c\n",
-		 nouveau_encoder_connector_get(nv_encoder)->base.name,
+		 nv04_encoder_get_connector(nv_encoder)->base.name,
 		 nv_crtc->index, '@' + ffs(nv_encoder->dcb->or));
 }
 
diff --git a/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c b/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
index 3a9489ed6544f..be28e7bd74903 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/tvnv17.c
@@ -599,7 +599,7 @@ static void nv17_tv_commit(struct drm_encoder *encoder)
 	helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
 	NV_INFO(drm, "Output %s is running on CRTC %d using output %c\n",
-		nouveau_encoder_connector_get(nv_encoder)->base.name,
+		nv04_encoder_get_connector(nv_encoder)->base.name,
 		nv_crtc->index, '@' + ffs(nv_encoder->dcb->or));
 }
 
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index c4d138f0ca054..255a281249bc8 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -411,6 +411,40 @@ nv50_outp_atomic_check(struct drm_encoder *encoder,
 	return 0;
 }
 
+struct nouveau_connector *
+nv50_outp_get_new_connector(struct nouveau_encoder *outp,
+			    struct drm_atomic_state *state)
+{
+	struct drm_connector *connector;
+	struct drm_connector_state *connector_state;
+	struct drm_encoder *encoder = to_drm_encoder(outp);
+	int i;
+
+	for_each_new_connector_in_state(state, connector, connector_state, i) {
+		if (connector_state->best_encoder == encoder)
+			return nouveau_connector(connector);
+	}
+
+	return NULL;
+}
+
+struct nouveau_connector *
+nv50_outp_get_old_connector(struct nouveau_encoder *outp,
+			    struct drm_atomic_state *state)
+{
+	struct drm_connector *connector;
+	struct drm_connector_state *connector_state;
+	struct drm_encoder *encoder = to_drm_encoder(outp);
+	int i;
+
+	for_each_old_connector_in_state(state, connector, connector_state, i) {
+		if (connector_state->best_encoder == encoder)
+			return nouveau_connector(connector);
+	}
+
+	return NULL;
+}
+
 /******************************************************************************
  * DAC
  *****************************************************************************/
@@ -552,16 +586,31 @@ nv50_audio_component_get_eld(struct device *kdev, int port, int dev_id,
 	struct nouveau_drm *drm = nouveau_drm(drm_dev);
 	struct drm_encoder *encoder;
 	struct nouveau_encoder *nv_encoder;
-	struct nouveau_connector *nv_connector;
+	struct drm_connector *connector;
 	struct nouveau_crtc *nv_crtc;
+	struct drm_connector_list_iter conn_iter;
 	int ret = 0;
 
 	*enabled = false;
+
 	drm_for_each_encoder(encoder, drm->dev) {
+		struct nouveau_connector *nv_connector = NULL;
+
 		nv_encoder = nouveau_encoder(encoder);
-		nv_connector = nouveau_encoder_connector_get(nv_encoder);
+
+		drm_connector_list_iter_begin(drm_dev, &conn_iter);
+		drm_for_each_connector_iter(connector, &conn_iter) {
+			if (connector->state->best_encoder == encoder) {
+				nv_connector = nouveau_connector(connector);
+				break;
+			}
+		}
+		drm_connector_list_iter_end(&conn_iter);
+		if (!nv_connector)
+			continue;
+
 		nv_crtc = nouveau_crtc(encoder->crtc);
-		if (!nv_connector || !nv_crtc || nv_encoder->or != port ||
+		if (!nv_crtc || nv_encoder->or != port ||
 		    nv_crtc->index != dev_id)
 			continue;
 		*enabled = nv_encoder->audio;
@@ -572,6 +621,7 @@ nv50_audio_component_get_eld(struct device *kdev, int port, int dev_id,
 		}
 		break;
 	}
+
 	return ret;
 }
 
@@ -665,7 +715,8 @@ nv50_audio_disable(struct drm_encoder *encoder, struct nouveau_crtc *nv_crtc)
 }
 
 static void
-nv50_audio_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
+nv50_audio_enable(struct drm_encoder *encoder, struct drm_atomic_state *state,
+		  struct drm_display_mode *mode)
 {
 	struct nouveau_drm *drm = nouveau_drm(encoder->dev);
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
@@ -686,7 +737,7 @@ nv50_audio_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
 				     (0x0100 << nv_crtc->index),
 	};
 
-	nv_connector = nouveau_encoder_connector_get(nv_encoder);
+	nv_connector = nv50_outp_get_new_connector(nv_encoder, state);
 	if (!drm_detect_monitor_audio(nv_connector->edid))
 		return;
 
@@ -723,7 +774,8 @@ nv50_hdmi_disable(struct drm_encoder *encoder, struct nouveau_crtc *nv_crtc)
 }
 
 static void
-nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
+nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_atomic_state *state,
+		 struct drm_display_mode *mode)
 {
 	struct nouveau_drm *drm = nouveau_drm(encoder->dev);
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
@@ -752,7 +804,7 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
 	int ret;
 	int size;
 
-	nv_connector = nouveau_encoder_connector_get(nv_encoder);
+	nv_connector = nv50_outp_get_new_connector(nv_encoder, state);
 	if (!drm_detect_hdmi_monitor(nv_connector->edid))
 		return;
 
@@ -798,7 +850,7 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
 		+ args.pwr.vendor_infoframe_length;
 	nvif_mthd(&disp->disp->object, 0, &args, size);
 
-	nv50_audio_enable(encoder, mode);
+	nv50_audio_enable(encoder, state, mode);
 
 	/* If SCDC is supported by the downstream monitor, update
 	 * divider / scrambling settings to what we programmed above.
@@ -1573,7 +1625,8 @@ nv50_sor_update(struct nouveau_encoder *nv_encoder, u8 head,
 }
 
 static void
-nv50_sor_disable(struct drm_encoder *encoder)
+nv50_sor_disable(struct drm_encoder *encoder,
+		 struct drm_atomic_state *state)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_crtc *nv_crtc = nouveau_crtc(nv_encoder->crtc);
@@ -1601,7 +1654,8 @@ nv50_sor_disable(struct drm_encoder *encoder)
 }
 
 static void
-nv50_sor_enable(struct drm_encoder *encoder)
+nv50_sor_enable(struct drm_encoder *encoder,
+		struct drm_atomic_state *state)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_crtc *nv_crtc = nouveau_crtc(encoder->crtc);
@@ -1625,7 +1679,7 @@ nv50_sor_enable(struct drm_encoder *encoder)
 	u8 proto = NV507D_SOR_SET_CONTROL_PROTOCOL_CUSTOM;
 	u8 depth = NV837D_SOR_SET_CONTROL_PIXEL_DEPTH_DEFAULT;
 
-	nv_connector = nouveau_encoder_connector_get(nv_encoder);
+	nv_connector = nv50_outp_get_new_connector(nv_encoder, state);
 	nv_encoder->crtc = encoder->crtc;
 
 	if ((disp->disp->object.oclass == GT214_DISP ||
@@ -1652,7 +1706,7 @@ nv50_sor_enable(struct drm_encoder *encoder)
 			proto = NV507D_SOR_SET_CONTROL_PROTOCOL_SINGLE_TMDS_B;
 		}
 
-		nv50_hdmi_enable(&nv_encoder->base.base, mode);
+		nv50_hdmi_enable(&nv_encoder->base.base, state, mode);
 		break;
 	case DCB_OUTPUT_LVDS:
 		proto = NV507D_SOR_SET_CONTROL_PROTOCOL_LVDS_CUSTOM;
@@ -1693,7 +1747,7 @@ nv50_sor_enable(struct drm_encoder *encoder)
 		else
 			proto = NV887D_SOR_SET_CONTROL_PROTOCOL_DP_B;
 
-		nv50_audio_enable(encoder, mode);
+		nv50_audio_enable(encoder, state, mode);
 		break;
 	default:
 		BUG();
@@ -1706,8 +1760,8 @@ nv50_sor_enable(struct drm_encoder *encoder)
 static const struct drm_encoder_helper_funcs
 nv50_sor_help = {
 	.atomic_check = nv50_outp_atomic_check,
-	.enable = nv50_sor_enable,
-	.disable = nv50_sor_disable,
+	.atomic_enable = nv50_sor_enable,
+	.atomic_disable = nv50_sor_disable,
 };
 
 static void
@@ -2066,7 +2120,7 @@ nv50_disp_atomic_commit_tail(struct drm_atomic_state *state)
 			  outp->clr.mask, outp->set.mask);
 
 		if (outp->clr.mask) {
-			help->disable(encoder);
+			help->atomic_disable(encoder, state);
 			interlock[NV50_DISP_INTERLOCK_CORE] |= 1;
 			if (outp->flush_disable) {
 				nv50_disp_atomic_commit_wndw(state, interlock);
@@ -2105,7 +2159,7 @@ nv50_disp_atomic_commit_tail(struct drm_atomic_state *state)
 			  outp->set.mask, outp->clr.mask);
 
 		if (outp->set.mask) {
-			help->enable(encoder);
+			help->atomic_enable(encoder, state);
 			interlock[NV50_DISP_INTERLOCK_CORE] = 1;
 		}
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index e12957e6faa7c..1d5696c39792a 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -391,20 +391,6 @@ find_encoder(struct drm_connector *connector, int type)
 	return NULL;
 }
 
-struct nouveau_connector *
-nouveau_encoder_connector_get(struct nouveau_encoder *encoder)
-{
-	struct drm_device *dev = to_drm_encoder(encoder)->dev;
-	struct drm_connector *drm_connector;
-
-	list_for_each_entry(drm_connector, &dev->mode_config.connector_list, head) {
-		if (drm_connector->encoder == to_drm_encoder(encoder))
-			return nouveau_connector(drm_connector);
-	}
-
-	return NULL;
-}
-
 static void
 nouveau_connector_destroy(struct drm_connector *connector)
 {
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index 6424cdcb4913f..b0e1dad2367d6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -113,7 +113,11 @@ enum drm_mode_status nv50_dp_mode_valid(struct drm_connector *,
 					unsigned *clock);
 
 struct nouveau_connector *
-nouveau_encoder_connector_get(struct nouveau_encoder *encoder);
+nv50_outp_get_new_connector(struct nouveau_encoder *outp,
+			    struct drm_atomic_state *state);
+struct nouveau_connector *
+nv50_outp_get_old_connector(struct nouveau_encoder *outp,
+			    struct drm_atomic_state *state);
 
 int nv50_mstm_detect(struct nv50_mstm *, u8 dpcd[8], int allow);
 void nv50_mstm_remove(struct nv50_mstm *);
-- 
2.26.2

[PATCH v5 07/20] drm/nouveau/kms/nv50-: Use drm_dp_dpcd_(readb|writeb)() in nv50_sor_disable()

[Lyude Paul]

Just use drm_dp_dpcd_(readb|writeb)() so we get automatic DPCD logging

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 255a281249bc8..612d98fa0a2dc 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1630,19 +1630,22 @@ nv50_sor_disable(struct drm_encoder *encoder,
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_crtc *nv_crtc = nouveau_crtc(nv_encoder->crtc);
+	struct nouveau_connector *nv_connector =
+		nv50_outp_get_old_connector(nv_encoder, state);
 
 	nv_encoder->crtc = NULL;
 
 	if (nv_crtc) {
-		struct nvkm_i2c_aux *aux = nv_encoder->aux;
+		struct drm_dp_aux *aux = &nv_connector->aux;
 		u8 pwr;
 
-		if (aux) {
-			int ret = nvkm_rdaux(aux, DP_SET_POWER, &pwr, 1);
+		if (nv_encoder->dcb->type == DCB_OUTPUT_DP) {
+			int ret = drm_dp_dpcd_readb(aux, DP_SET_POWER, &pwr);
+
 			if (ret == 0) {
 				pwr &= ~DP_SET_POWER_MASK;
 				pwr |=  DP_SET_POWER_D3;
-				nvkm_wraux(aux, DP_SET_POWER, &pwr, 1);
+				drm_dp_dpcd_writeb(aux, DP_SET_POWER, pwr);
 			}
 		}
 
-- 
2.26.2

[PATCH v5 08/20] drm/nouveau/kms/nv50-: Refactor and cleanup DP HPD handling

[Lyude Paul]

First some backstory here: Currently, we keep track of whether or not
we've enabled MST or not by trying to piggy-back off the MST helpers.
This means that in order to check whether MST is enabled or not, we
actually need to grab drm_dp_mst_topology_mgr.lock.

Back when I originally wrote this, I did this piggy-backing with the
intention that I'd eventually be teaching our MST helpers how to recover
when an MST device has stopped responding, which in turn would require
the MST helpers having a way of disabling MST independently of the
driver. Note that this was before I reworked locking in the MST helpers,
so at the time we were sticking random things under &mgr->lock - which
grabbing this lock was meant to protect against.

This never came to fruition because doing such a reset safely turned out
to be a lot more painful and impossible then it sounds, and also just
risks us working around issues with our MST handlers that should be
properly fixed instead. Even if it did though, simply calling
drm_dp_mst_topology_mgr_set_mst() from the MST helpers (with the
exception of when we're tearing down our MST managers, that's always OK)
wouldn't have been a bad idea, since drivers like nouveau and i915 need
to do their own book keeping immediately after disabling MST.
So-implementing that would likely require adding a hook for
helper-triggered MST disables anyway.

So, fast forward to now - we want to start adding support for all of the
miscellaneous bits of the DP protocol (for both SST and MST) we're
missing before moving on to supporting more complicated features like
supporting different BPP values on MST, DSC, etc. Since many of these
features only exist on SST and make use of DP HPD IRQs, we want to be
able to atomically check whether we're servicing an MST IRQ or SST IRQ
in nouveau_connector_hotplug(). Currently we literally don't do this at
all, and just handle any kind of possible DP IRQ we could get including
ESIs - even if MST isn't actually enabled.

This would be very complicated and difficult to fix if we need to hold
&mgr->lock while handling SST IRQs to ensure that the MST topology
state doesn't change under us. What we really want here is to do our own
tracking of whether MST is enabled or not, similar to drivers like i915,
and define our own locking order to decomplicate things and avoid
hitting locking issues in the future.

So, let's do this by refactoring our MST probing/enabling code to use
our own MST bookkeeping, along with adding a lock for protecting DP
state that needs to be checked outside of our connector probing
functions. While we're at it, we also remove a bunch of unneeded steps
we perform when probing/enabling MST:

* Enabling bits in MSTM_CTRL before calling drm_dp_mst_topology_mgr_set_mst().
  I don't think these ever actually did anything, since the nvif methods
  for enabling MST don't actually do anything DPCD related and merely
  indicate to nvkm that we've turned on MST.
* Checking the MSTM_CTRL bit is intact when checking the state of an
  enabled MST topology in nv50_mstm_detect(). I just added this to be safe
  originally, but now that we try reading the DPCD when probing DP
  connectors it shouldn't be needed as that will abort our hotplug probing
  if the device was removed well before we start checking for MST..
* All of the duplicate DPCD version checks.

This leaves us with much nicer looking code, a much more sensible
locking scheme, and an easy way of checking whether MST is enabled or
not for handling DP HPD IRQs.

v2:
* Get rid of accidental newlines
v4:
* Fix uninitialized usage of mstm in nv50_mstm_detect() - thanks kernel
  bot!

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv04/disp.c     |   6 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c     | 192 +++++++++-----------
 drivers/gpu/drm/nouveau/nouveau_connector.c |  14 +-
 drivers/gpu/drm/nouveau/nouveau_display.c   |   2 +-
 drivers/gpu/drm/nouveau/nouveau_display.h   |   2 +-
 drivers/gpu/drm/nouveau/nouveau_dp.c        | 132 ++++++++++++--
 drivers/gpu/drm/nouveau/nouveau_encoder.h   |  33 +++-
 7 files changed, 244 insertions(+), 137 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv04/disp.c b/drivers/gpu/drm/nouveau/dispnv04/disp.c
index 3f046b917c85c..3ee836dc5058f 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/disp.c
@@ -54,8 +54,9 @@ nv04_encoder_get_connector(struct nouveau_encoder *encoder)
 }
 
 static void
-nv04_display_fini(struct drm_device *dev, bool suspend)
+nv04_display_fini(struct drm_device *dev, bool runtime, bool suspend)
 {
+	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct nv04_display *disp = nv04_display(dev);
 	struct drm_crtc *crtc;
 
@@ -67,6 +68,9 @@ nv04_display_fini(struct drm_device *dev, bool suspend)
 	if (nv_two_heads(dev))
 		NVWriteCRTC(dev, 1, NV_PCRTC_INTR_EN_0, 0);
 
+	if (!runtime)
+		cancel_work_sync(&drm->hpd_work);
+
 	if (!suspend)
 		return;
 
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 612d98fa0a2dc..8e1effb10425d 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -879,16 +879,6 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_atomic_state *state,
 #define nv50_mstc(p) container_of((p), struct nv50_mstc, connector)
 #define nv50_msto(p) container_of((p), struct nv50_msto, encoder)
 
-struct nv50_mstm {
-	struct nouveau_encoder *outp;
-
-	struct drm_dp_mst_topology_mgr mgr;
-
-	bool modified;
-	bool disabled;
-	int links;
-};
-
 struct nv50_mstc {
 	struct nv50_mstm *mstm;
 	struct drm_dp_mst_port *port;
@@ -1417,41 +1407,51 @@ nv50_mstm = {
 	.add_connector = nv50_mstm_add_connector,
 };
 
-void
-nv50_mstm_service(struct nv50_mstm *mstm)
+bool
+nv50_mstm_service(struct nouveau_drm *drm,
+		  struct nouveau_connector *nv_connector,
+		  struct nv50_mstm *mstm)
 {
-	struct drm_dp_aux *aux = mstm ? mstm->mgr.aux : NULL;
-	bool handled = true;
-	int ret;
+	struct drm_dp_aux *aux = &nv_connector->aux;
+	bool handled = true, ret = true;
+	int rc;
 	u8 esi[8] = {};
 
-	if (!aux)
-		return;
-
 	while (handled) {
-		ret = drm_dp_dpcd_read(aux, DP_SINK_COUNT_ESI, esi, 8);
-		if (ret != 8) {
-			drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
-			return;
+		rc = drm_dp_dpcd_read(aux, DP_SINK_COUNT_ESI, esi, 8);
+		if (rc != 8) {
+			ret = false;
+			break;
 		}
 
 		drm_dp_mst_hpd_irq(&mstm->mgr, esi, &handled);
 		if (!handled)
 			break;
 
-		drm_dp_dpcd_write(aux, DP_SINK_COUNT_ESI + 1, &esi[1], 3);
+		rc = drm_dp_dpcd_write(aux, DP_SINK_COUNT_ESI + 1, &esi[1],
+				       3);
+		if (rc != 3) {
+			ret = false;
+			break;
+		}
 	}
+
+	if (!ret)
+		NV_DEBUG(drm, "Failed to handle ESI on %s: %d\n",
+			 nv_connector->base.name, rc);
+
+	return ret;
 }
 
 void
 nv50_mstm_remove(struct nv50_mstm *mstm)
 {
-	if (mstm)
-		drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
+	mstm->is_mst = false;
+	drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
 }
 
 static int
-nv50_mstm_enable(struct nv50_mstm *mstm, u8 dpcd, int state)
+nv50_mstm_enable(struct nv50_mstm *mstm, int state)
 {
 	struct nouveau_encoder *outp = mstm->outp;
 	struct {
@@ -1466,106 +1466,85 @@ nv50_mstm_enable(struct nv50_mstm *mstm, u8 dpcd, int state)
 	};
 	struct nouveau_drm *drm = nouveau_drm(outp->base.base.dev);
 	struct nvif_object *disp = &drm->display->disp.object;
-	int ret;
-
-	if (dpcd >= 0x12) {
-		/* Even if we're enabling MST, start with disabling the
-		 * branching unit to clear any sink-side MST topology state
-		 * that wasn't set by us
-		 */
-		ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL, 0);
-		if (ret < 0)
-			return ret;
-
-		if (state) {
-			/* Now, start initializing */
-			ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL,
-						 DP_MST_EN);
-			if (ret < 0)
-				return ret;
-		}
-	}
 
 	return nvif_mthd(disp, 0, &args, sizeof(args));
 }
 
 int
-nv50_mstm_detect(struct nv50_mstm *mstm, u8 dpcd[8], int allow)
+nv50_mstm_detect(struct nouveau_encoder *outp)
 {
+	struct nv50_mstm *mstm = outp->dp.mstm;
 	struct drm_dp_aux *aux;
 	int ret;
-	bool old_state, new_state;
-	u8 mstm_ctrl;
 
-	if (!mstm)
+	if (!mstm || !mstm->can_mst)
 		return 0;
 
-	mutex_lock(&mstm->mgr.lock);
-
-	old_state = mstm->mgr.mst_state;
-	new_state = old_state;
 	aux = mstm->mgr.aux;
 
-	if (old_state) {
-		/* Just check that the MST hub is still as we expect it */
-		ret = drm_dp_dpcd_readb(aux, DP_MSTM_CTRL, &mstm_ctrl);
-		if (ret < 0 || !(mstm_ctrl & DP_MST_EN)) {
-			DRM_DEBUG_KMS("Hub gone, disabling MST topology\n");
-			new_state = false;
-		}
-	} else if (dpcd[0] >= 0x12) {
-		ret = drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &dpcd[1]);
-		if (ret < 0)
-			goto probe_error;
-
-		if (!(dpcd[1] & DP_MST_CAP))
-			dpcd[0] = 0x11;
-		else
-			new_state = allow;
-	}
-
-	if (new_state == old_state) {
-		mutex_unlock(&mstm->mgr.lock);
-		return new_state;
-	}
-
-	ret = nv50_mstm_enable(mstm, dpcd[0], new_state);
-	if (ret)
-		goto probe_error;
-
-	mutex_unlock(&mstm->mgr.lock);
+	/* Clear any leftover MST state we didn't set ourselves by first
+	 * disabling MST if it was already enabled
+	 */
+	ret = drm_dp_dpcd_writeb(aux, DP_MSTM_CTRL, 0);
+	if (ret < 0)
+		return ret;
 
-	ret = drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, new_state);
+	/* And start enabling */
+	ret = nv50_mstm_enable(mstm, true);
 	if (ret)
-		return nv50_mstm_enable(mstm, dpcd[0], 0);
+		return ret;
 
-	return new_state;
+	ret = drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, true);
+	if (ret) {
+		nv50_mstm_enable(mstm, false);
+		return ret;
+	}
 
-probe_error:
-	mutex_unlock(&mstm->mgr.lock);
-	return ret;
+	mstm->is_mst = true;
+	return 1;
 }
 
 static void
-nv50_mstm_fini(struct nv50_mstm *mstm)
+nv50_mstm_fini(struct nouveau_encoder *outp)
 {
-	if (mstm && mstm->mgr.mst_state)
+	struct nv50_mstm *mstm = outp->dp.mstm;
+
+	if (!mstm)
+		return;
+
+	/* Don't change the MST state of this connector until we've finished
+	 * resuming, since we can't safely grab hpd_irq_lock in our resume
+	 * path to protect mstm->is_mst without potentially deadlocking
+	 */
+	mutex_lock(&outp->dp.hpd_irq_lock);
+	mstm->suspended = true;
+	mutex_unlock(&outp->dp.hpd_irq_lock);
+
+	if (mstm->is_mst)
 		drm_dp_mst_topology_mgr_suspend(&mstm->mgr);
 }
 
 static void
-nv50_mstm_init(struct nv50_mstm *mstm, bool runtime)
+nv50_mstm_init(struct nouveau_encoder *outp, bool runtime)
 {
-	int ret;
+	struct nv50_mstm *mstm = outp->dp.mstm;
+	int ret = 0;
 
-	if (!mstm || !mstm->mgr.mst_state)
+	if (!mstm)
 		return;
 
-	ret = drm_dp_mst_topology_mgr_resume(&mstm->mgr, !runtime);
-	if (ret == -1) {
-		drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
-		drm_kms_helper_hotplug_event(mstm->mgr.dev);
+	if (mstm->is_mst) {
+		ret = drm_dp_mst_topology_mgr_resume(&mstm->mgr, !runtime);
+		if (ret == -1)
+			nv50_mstm_remove(mstm);
 	}
+
+	mutex_lock(&outp->dp.hpd_irq_lock);
+	mstm->suspended = false;
+	mutex_unlock(&outp->dp.hpd_irq_lock);
+
+	if (ret == -1)
+		drm_kms_helper_hotplug_event(mstm->mgr.dev);
 }
 
 static void
@@ -1773,6 +1752,10 @@ nv50_sor_destroy(struct drm_encoder *encoder)
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	nv50_mstm_del(&nv_encoder->dp.mstm);
 	drm_encoder_cleanup(encoder);
+
+	if (nv_encoder->dcb->type == DCB_OUTPUT_DP)
+		mutex_destroy(&nv_encoder->dp.hpd_irq_lock);
+
 	kfree(encoder);
 }
 
@@ -1832,6 +1815,8 @@ nv50_sor_create(struct drm_connector *connector, struct dcb_output *dcbe)
 		struct nvkm_i2c_aux *aux =
 			nvkm_i2c_aux_find(i2c, dcbe->i2c_index);
 
+		mutex_init(&nv_encoder->dp.hpd_irq_lock);
+
 		if (aux) {
 			if (disp->disp->object.oclass < GF110_DISP) {
 				/* HW has no support for address-only
@@ -2530,9 +2515,9 @@ nv50_disp_func = {
  *****************************************************************************/
 
 static void
-nv50_display_fini(struct drm_device *dev, bool suspend)
+nv50_display_fini(struct drm_device *dev, bool runtime, bool suspend)
 {
-	struct nouveau_encoder *nv_encoder;
+	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct drm_encoder *encoder;
 	struct drm_plane *plane;
 
@@ -2544,11 +2529,12 @@ nv50_display_fini(struct drm_device *dev, bool suspend)
 	}
 
 	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
-		if (encoder->encoder_type != DRM_MODE_ENCODER_DPMST) {
-			nv_encoder = nouveau_encoder(encoder);
-			nv50_mstm_fini(nv_encoder->dp.mstm);
-		}
+		if (encoder->encoder_type != DRM_MODE_ENCODER_DPMST)
+			nv50_mstm_fini(nouveau_encoder(encoder));
 	}
+
+	if (!runtime)
+		cancel_work_sync(&drm->hpd_work);
 }
 
 static int
@@ -2565,7 +2551,7 @@ nv50_display_init(struct drm_device *dev, bool resume, bool runtime)
 		if (encoder->encoder_type != DRM_MODE_ENCODER_DPMST) {
 			struct nouveau_encoder *nv_encoder =
 				nouveau_encoder(encoder);
-			nv50_mstm_init(nv_encoder->dp.mstm, runtime);
+			nv50_mstm_init(nv_encoder, runtime);
 		}
 	}
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 1d5696c39792a..b90591114faaf 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -1143,19 +1143,15 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 	struct nouveau_connector *nv_connector =
 		container_of(notify, typeof(*nv_connector), hpd);
 	struct drm_connector *connector = &nv_connector->base;
-	struct nouveau_drm *drm = nouveau_drm(connector->dev);
+	struct drm_device *dev = connector->dev;
+	struct nouveau_drm *drm = nouveau_drm(dev);
 	const struct nvif_notify_conn_rep_v0 *rep = notify->data;
 	const char *name = connector->name;
-	struct nouveau_encoder *nv_encoder;
 	int ret;
 	bool plugged = (rep->mask != NVIF_NOTIFY_CONN_V0_UNPLUG);
 
 	if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
-		NV_DEBUG(drm, "service %s\n", name);
-		drm_dp_cec_irq(&nv_connector->aux);
-		if ((nv_encoder = find_encoder(connector, DCB_OUTPUT_DP)))
-			nv50_mstm_service(nv_encoder->dp.mstm);
-
+		nouveau_dp_irq(drm, nv_connector);
 		return NVIF_NOTIFY_KEEP;
 	}
 
@@ -1181,10 +1177,6 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 	if (!plugged)
 		drm_dp_cec_unset_edid(&nv_connector->aux);
 	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", name);
-	if ((nv_encoder = find_encoder(connector, DCB_OUTPUT_DP))) {
-		if (!plugged)
-			nv50_mstm_remove(nv_encoder->dp.mstm);
-	}
 
 	drm_helper_hpd_irq_event(connector->dev);
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index 5f31b11ac2e7e..13016769a194b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -569,7 +569,7 @@ nouveau_display_fini(struct drm_device *dev, bool suspend, bool runtime)
 		cancel_work_sync(&drm->hpd_work);
 
 	drm_kms_helper_poll_disable(dev);
-	disp->fini(dev, suspend);
+	disp->fini(dev, runtime, suspend);
 }
 
 static void
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.h b/drivers/gpu/drm/nouveau/nouveau_display.h
index 6e0d900441d69..76ba93e01aff4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.h
+++ b/drivers/gpu/drm/nouveau/nouveau_display.h
@@ -18,7 +18,7 @@ struct nouveau_display {
 	void *priv;
 	void (*dtor)(struct drm_device *);
 	int  (*init)(struct drm_device *, bool resume, bool runtime);
-	void (*fini)(struct drm_device *, bool suspend);
+	void (*fini)(struct drm_device *, bool suspend, bool runtime);
 
 	struct nvif_disp disp;
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 4030806e3522b..032afc73e2a33 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -36,19 +36,89 @@ MODULE_PARM_DESC(mst, "Enable DisplayPort multi-stream (default: enabled)");
 static int nouveau_mst = 1;
 module_param_named(mst, nouveau_mst, int, 0400);
 
+static enum drm_connector_status
+nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
+		      struct nouveau_encoder *outp)
+{
+	struct drm_dp_aux *aux = &nv_connector->aux;
+	struct nv50_mstm *mstm = NULL;
+	int ret;
+	u8 *dpcd = outp->dp.dpcd;
+	u8 tmp;
+
+	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
+	if (ret == DP_RECEIVER_CAP_SIZE && dpcd[DP_DPCD_REV]) {
+		ret = drm_dp_read_desc(aux, &outp->dp.desc,
+				       drm_dp_is_branch(dpcd));
+		if (ret < 0)
+			return connector_status_disconnected;
+	} else {
+		return connector_status_disconnected;
+	}
+
+	if (nouveau_mst)
+		mstm = outp->dp.mstm;
+
+	if (mstm) {
+		if (dpcd[DP_DPCD_REV] >= DP_DPCD_REV_12) {
+			ret = drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &tmp);
+			if (ret < 0)
+				return connector_status_disconnected;
+
+			mstm->can_mst = !!(tmp & DP_MST_CAP);
+		} else {
+			mstm->can_mst = false;
+		}
+	}
+
+	return connector_status_connected;
+}
+
 int
 nouveau_dp_detect(struct nouveau_connector *nv_connector,
 		  struct nouveau_encoder *nv_encoder)
 {
 	struct drm_device *dev = nv_encoder->base.base.dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
-	struct drm_dp_aux *aux = &nv_connector->aux;
-	u8 dpcd[DP_RECEIVER_CAP_SIZE];
-	int ret;
+	struct drm_connector *connector = &nv_connector->base;
+	struct nv50_mstm *mstm = nv_encoder->dp.mstm;
+	enum drm_connector_status status;
+	u8 *dpcd = nv_encoder->dp.dpcd;
+	int ret = NOUVEAU_DP_NONE;
+
+	/* If we've already read the DPCD on an eDP device, we don't need to
+	 * reread it as it won't change
+	 */
+	if (connector->connector_type == DRM_MODE_CONNECTOR_eDP &&
+	    dpcd[DP_DPCD_REV] != 0)
+		return NOUVEAU_DP_SST;
 
-	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
-	if (ret != sizeof(dpcd))
-		return ret;
+	mutex_lock(&nv_encoder->dp.hpd_irq_lock);
+	if (mstm) {
+		/* If we're not ready to handle MST state changes yet, just
+		 * report the last status of the connector. We'll reprobe it
+		 * once we've resumed.
+		 */
+		if (mstm->suspended) {
+			if (mstm->is_mst)
+				ret = NOUVEAU_DP_MST;
+			else if (connector->status ==
+				 connector_status_connected)
+				ret = NOUVEAU_DP_SST;
+
+			goto out;
+		}
+	}
+
+	status = nouveau_dp_probe_dpcd(nv_connector, nv_encoder);
+	if (status == connector_status_disconnected)
+		goto out;
+
+	/* If we're in MST mode, we're done here */
+	if (mstm && mstm->can_mst && mstm->is_mst) {
+		ret = NOUVEAU_DP_MST;
+		goto out;
+	}
 
 	nv_encoder->dp.link_bw = 27000 * dpcd[DP_MAX_LINK_RATE];
 	nv_encoder->dp.link_nr =
@@ -69,22 +139,50 @@ nouveau_dp_detect(struct nouveau_connector *nv_connector,
 	NV_DEBUG(drm, "maximum: %dx%d\n",
 		 nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
 
-	ret = drm_dp_read_desc(&nv_connector->aux, &nv_encoder->dp.desc,
-			       drm_dp_is_branch(dpcd));
-	if (ret) {
-		NV_ERROR(drm, "Failed to read DP descriptor on %s: %d\n",
-			 nv_connector->base.name, ret);
-		return ret;
+	if (mstm && mstm->can_mst) {
+		ret = nv50_mstm_detect(nv_encoder);
+		if (ret == 1) {
+			ret = NOUVEAU_DP_MST;
+			goto out;
+		} else if (ret != 0) {
+			goto out;
+		}
 	}
+	ret = NOUVEAU_DP_SST;
 
-	ret = nv50_mstm_detect(nv_encoder->dp.mstm, dpcd, nouveau_mst);
-	if (ret == 1)
-		return NOUVEAU_DP_MST;
-	if (ret == 0)
-		return NOUVEAU_DP_SST;
+out:
+	if (mstm && !mstm->suspended && ret != NOUVEAU_DP_MST)
+		nv50_mstm_remove(mstm);
+
+	mutex_unlock(&nv_encoder->dp.hpd_irq_lock);
 	return ret;
 }
 
+void nouveau_dp_irq(struct nouveau_drm *drm,
+		    struct nouveau_connector *nv_connector)
+{
+	struct drm_connector *connector = &nv_connector->base;
+	struct nouveau_encoder *outp = find_encoder(connector, DCB_OUTPUT_DP);
+	struct nv50_mstm *mstm;
+
+	if (!outp)
+		return;
+
+	mstm = outp->dp.mstm;
+	NV_DEBUG(drm, "service %s\n", connector->name);
+
+	mutex_lock(&outp->dp.hpd_irq_lock);
+
+	if (mstm && mstm->is_mst) {
+		if (!nv50_mstm_service(drm, nv_connector, mstm))
+			schedule_work(&drm->hpd_work);
+	} else {
+		drm_dp_cec_irq(&nv_connector->aux);
+	}
+
+	mutex_unlock(&outp->dp.hpd_irq_lock);
+}
+
 /* TODO:
  * - Use the minimum possible BPC here, once we add support for the max bpc
  *   property.
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index b0e1dad2367d6..eef4643f5f982 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -65,6 +65,13 @@ struct nouveau_encoder {
 			struct nv50_mstm *mstm;
 			int link_nr;
 			int link_bw;
+
+			/* Protects DP state that needs to be accessed outside
+			 * connector reprobing contexts
+			 */
+			struct mutex hpd_irq_lock;
+
+			u8 dpcd[DP_RECEIVER_CAP_SIZE];
 			struct drm_dp_desc desc;
 		} dp;
 	};
@@ -79,6 +86,21 @@ struct nouveau_encoder {
 		       struct nv50_head_atom *, u8 proto, u8 depth);
 };
 
+struct nv50_mstm {
+	struct nouveau_encoder *outp;
+
+	struct drm_dp_mst_topology_mgr mgr;
+
+	/* Protected under nouveau_encoder->dp.hpd_irq_lock */
+	bool can_mst;
+	bool is_mst;
+	bool suspended;
+
+	bool modified;
+	bool disabled;
+	int links;
+};
+
 struct nouveau_encoder *
 find_encoder(struct drm_connector *connector, int type);
 
@@ -102,11 +124,14 @@ get_slave_funcs(struct drm_encoder *enc)
 
 /* nouveau_dp.c */
 enum nouveau_dp_status {
+	NOUVEAU_DP_NONE,
 	NOUVEAU_DP_SST,
 	NOUVEAU_DP_MST,
 };
 
 int nouveau_dp_detect(struct nouveau_connector *, struct nouveau_encoder *);
+void nouveau_dp_irq(struct nouveau_drm *drm,
+		    struct nouveau_connector *nv_connector);
 enum drm_mode_status nv50_dp_mode_valid(struct drm_connector *,
 					struct nouveau_encoder *,
 					const struct drm_display_mode *,
@@ -119,7 +144,9 @@ struct nouveau_connector *
 nv50_outp_get_old_connector(struct nouveau_encoder *outp,
 			    struct drm_atomic_state *state);
 
-int nv50_mstm_detect(struct nv50_mstm *, u8 dpcd[8], int allow);
-void nv50_mstm_remove(struct nv50_mstm *);
-void nv50_mstm_service(struct nv50_mstm *);
+int nv50_mstm_detect(struct nouveau_encoder *encoder);
+void nv50_mstm_remove(struct nv50_mstm *mstm);
+bool nv50_mstm_service(struct nouveau_drm *drm,
+		       struct nouveau_connector *nv_connector,
+		       struct nv50_mstm *mstm);
 #endif /* __NOUVEAU_ENCODER_H__ */
-- 
2.26.2

[PATCH v5 09/20] drm/i915/dp: Extract drm_dp_read_mst_cap()

[Lyude Paul]

Just a tiny drive-by cleanup, we can consolidate i915's code for
checking for MST support into a helper to be shared across drivers.

v5:
* Drop !!()
* Move drm_dp_has_mst() out of header
* Change name from drm_dp_has_mst() to drm_dp_read_mst_cap()

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Sean Paul <sean@poorly.run>
---
 drivers/gpu/drm/drm_dp_mst_topology.c   | 22 ++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c | 18 ++----------------
 include/drm/drm_dp_mst_helper.h         |  3 +--
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 67dd72ea200e0..17dbed0a9800d 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3486,6 +3486,28 @@ static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8  dp_link_count)
 	return dp_link_bw * dp_link_count / 2;
 }
 
+/**
+ * drm_dp_read_mst_cap() - check whether or not a sink supports MST
+ * @aux: The DP AUX channel to use
+ * @dpcd: A cached copy of the DPCD capabilities for this sink
+ *
+ * Returns: %True if the sink supports MST, %false otherwise
+ */
+bool drm_dp_read_mst_cap(struct drm_dp_aux *aux,
+			 const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 mstm_cap;
+
+	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
+		return false;
+
+	if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
+		return false;
+
+	return mstm_cap & DP_MST_CAP;
+}
+EXPORT_SYMBOL(drm_dp_read_mst_cap);
+
 /**
  * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
  * @mgr: manager to set state for
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 79c27f91f42c0..4c7314b7a84e4 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4699,20 +4699,6 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 	return true;
 }
 
-static bool
-intel_dp_sink_can_mst(struct intel_dp *intel_dp)
-{
-	u8 mstm_cap;
-
-	if (intel_dp->dpcd[DP_DPCD_REV] < 0x12)
-		return false;
-
-	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_MSTM_CAP, &mstm_cap) != 1)
-		return false;
-
-	return mstm_cap & DP_MST_CAP;
-}
-
 static bool
 intel_dp_can_mst(struct intel_dp *intel_dp)
 {
@@ -4720,7 +4706,7 @@ intel_dp_can_mst(struct intel_dp *intel_dp)
 
 	return i915->params.enable_dp_mst &&
 		intel_dp->can_mst &&
-		intel_dp_sink_can_mst(intel_dp);
+		drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd);
 }
 
 static void
@@ -4729,7 +4715,7 @@ intel_dp_configure_mst(struct intel_dp *intel_dp)
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	struct intel_encoder *encoder =
 		&dp_to_dig_port(intel_dp)->base;
-	bool sink_can_mst = intel_dp_sink_can_mst(intel_dp);
+	bool sink_can_mst = drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd);
 
 	drm_dbg_kms(&i915->drm,
 		    "[ENCODER:%d:%s] MST support: port: %s, sink: %s, modparam: %s\n",
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 8b9eb4db3381c..6ae5860d8644e 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -728,10 +728,9 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
 
 void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr);
 
-
+bool drm_dp_read_mst_cap(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
 int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state);
 
-
 int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled);
 
 
-- 
2.26.2

Re: [PATCH v5 09/20] drm/i915/dp: Extract drm_dp_read_mst_cap()

[Jani Nikula]

On Wed, 26 Aug 2020, Lyude Paul <lyude@redhat.com> wrote:
> Just a tiny drive-by cleanup, we can consolidate i915's code for
> checking for MST support into a helper to be shared across drivers.
>
> v5:
> * Drop !!()
> * Move drm_dp_has_mst() out of header
> * Change name from drm_dp_has_mst() to drm_dp_read_mst_cap()
>
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Reviewed-by: Sean Paul <sean@poorly.run>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c   | 22 ++++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp.c | 18 ++----------------
>  include/drm/drm_dp_mst_helper.h         |  3 +--
>  3 files changed, 25 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 67dd72ea200e0..17dbed0a9800d 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -3486,6 +3486,28 @@ static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8  dp_link_count)
>  	return dp_link_bw * dp_link_count / 2;
>  }
>  
> +/**
> + * drm_dp_read_mst_cap() - check whether or not a sink supports MST
> + * @aux: The DP AUX channel to use
> + * @dpcd: A cached copy of the DPCD capabilities for this sink
> + *
> + * Returns: %True if the sink supports MST, %false otherwise
> + */
> +bool drm_dp_read_mst_cap(struct drm_dp_aux *aux,
> +			 const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> +{
> +	u8 mstm_cap;
> +
> +	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
> +		return false;
> +
> +	if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
> +		return false;
> +
> +	return mstm_cap & DP_MST_CAP;
> +}
> +EXPORT_SYMBOL(drm_dp_read_mst_cap);
> +
>  /**
>   * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
>   * @mgr: manager to set state for
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 79c27f91f42c0..4c7314b7a84e4 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4699,20 +4699,6 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  	return true;
>  }
>  
> -static bool
> -intel_dp_sink_can_mst(struct intel_dp *intel_dp)
> -{
> -	u8 mstm_cap;
> -
> -	if (intel_dp->dpcd[DP_DPCD_REV] < 0x12)
> -		return false;
> -
> -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_MSTM_CAP, &mstm_cap) != 1)
> -		return false;
> -
> -	return mstm_cap & DP_MST_CAP;
> -}
> -
>  static bool
>  intel_dp_can_mst(struct intel_dp *intel_dp)
>  {
> @@ -4720,7 +4706,7 @@ intel_dp_can_mst(struct intel_dp *intel_dp)
>  
>  	return i915->params.enable_dp_mst &&
>  		intel_dp->can_mst &&
> -		intel_dp_sink_can_mst(intel_dp);
> +		drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd);
>  }
>  
>  static void
> @@ -4729,7 +4715,7 @@ intel_dp_configure_mst(struct intel_dp *intel_dp)
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  	struct intel_encoder *encoder =
>  		&dp_to_dig_port(intel_dp)->base;
> -	bool sink_can_mst = intel_dp_sink_can_mst(intel_dp);
> +	bool sink_can_mst = drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd);
>  
>  	drm_dbg_kms(&i915->drm,
>  		    "[ENCODER:%d:%s] MST support: port: %s, sink: %s, modparam: %s\n",
> diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
> index 8b9eb4db3381c..6ae5860d8644e 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -728,10 +728,9 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
>  
>  void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr);
>  
> -
> +bool drm_dp_read_mst_cap(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
>  int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state);
>  
> -
>  int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled);

-- 
Jani Nikula, Intel Open Source Graphics Center

[PATCH v5 10/20] drm/nouveau/kms: Use new drm_dp_read_mst_cap() helper for checking MST caps

[Lyude Paul]

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 032afc73e2a33..a5934064a75ea 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -44,7 +44,6 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 	struct nv50_mstm *mstm = NULL;
 	int ret;
 	u8 *dpcd = outp->dp.dpcd;
-	u8 tmp;
 
 	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
 	if (ret == DP_RECEIVER_CAP_SIZE && dpcd[DP_DPCD_REV]) {
@@ -56,19 +55,10 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 		return connector_status_disconnected;
 	}
 
-	if (nouveau_mst)
+	if (nouveau_mst) {
 		mstm = outp->dp.mstm;
-
-	if (mstm) {
-		if (dpcd[DP_DPCD_REV] >= DP_DPCD_REV_12) {
-			ret = drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &tmp);
-			if (ret < 0)
-				return connector_status_disconnected;
-
-			mstm->can_mst = !!(tmp & DP_MST_CAP);
-		} else {
-			mstm->can_mst = false;
-		}
+		if (mstm)
+			mstm->can_mst = drm_dp_read_mst_cap(aux, dpcd);
 	}
 
 	return connector_status_connected;
-- 
2.26.2

[PATCH v5 11/20] drm/nouveau/kms: Move drm_dp_cec_unset_edid() into nouveau_connector_detect()

[Lyude Paul]

For whatever reason we currently unset the EDID for DP CEC support when
responding to the connector being unplugged, instead of just doing it in
nouveau_connector_detect() where we set the CEC EDID. This isn't really
needed and could even potentially cause us to forget to unset the EDID
if the connector is removed without a corresponding hpd event, so let's
fix that.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index b90591114faaf..4a29f691c08e4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -633,10 +633,11 @@ nouveau_connector_detect(struct drm_connector *connector, bool force)
 			conn_status = connector_status_connected;
 			goto out;
 		}
-
 	}
 
  out:
+	if (!nv_connector->edid)
+		drm_dp_cec_unset_edid(&nv_connector->aux);
 
 	pm_runtime_mark_last_busy(dev->dev);
 	pm_runtime_put_autosuspend(dev->dev);
@@ -1174,8 +1175,6 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 		return NVIF_NOTIFY_DROP;
 	}
 
-	if (!plugged)
-		drm_dp_cec_unset_edid(&nv_connector->aux);
 	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", name);
 
 	drm_helper_hpd_irq_event(connector->dev);
-- 
2.26.2

[PATCH v5 12/20] drm/nouveau/kms: Only use hpd_work for reprobing in HPD paths

[Lyude Paul]

Currently we perform both short IRQ handling for DP, and connector
reprobing in the HPD IRQ handler. However since we need to grab
connection_mutex in order to reprobe a connector, in theory we could
accidentally block ourselves from handling any short IRQs until after a
modeset completes if a connector hotplug happens to occur in parallel
with a modeset.

I haven't seen this actually happen yet, but since we're cleaning up
nouveau's hotplug handling code anyway and we already have a hpd worker,
we can simply fix this by only relying on the HPD worker to actually
reprobe connectors when we receive a HPD IRQ. We also add a mask to
nouveau_drm to keep track of which connectors are waiting to be reprobed
in response to an HPD IRQ.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 42 +++++--------
 drivers/gpu/drm/nouveau/nouveau_connector.h |  1 +
 drivers/gpu/drm/nouveau/nouveau_display.c   | 70 ++++++++++++++++++---
 drivers/gpu/drm/nouveau/nouveau_display.h   |  1 +
 drivers/gpu/drm/nouveau/nouveau_dp.c        |  2 +-
 drivers/gpu/drm/nouveau/nouveau_drm.c       |  4 +-
 drivers/gpu/drm/nouveau/nouveau_drv.h       |  2 +
 7 files changed, 86 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 4a29f691c08e4..637e91594fbe8 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -1138,6 +1138,20 @@ nouveau_connector_funcs_lvds = {
 	.early_unregister = nouveau_connector_early_unregister,
 };
 
+void
+nouveau_connector_hpd(struct drm_connector *connector)
+{
+	struct nouveau_drm *drm = nouveau_drm(connector->dev);
+	u32 mask = drm_connector_mask(connector);
+
+	mutex_lock(&drm->hpd_lock);
+	if (!(drm->hpd_pending & mask)) {
+		drm->hpd_pending |= mask;
+		schedule_work(&drm->hpd_work);
+	}
+	mutex_unlock(&drm->hpd_lock);
+}
+
 static int
 nouveau_connector_hotplug(struct nvif_notify *notify)
 {
@@ -1147,8 +1161,6 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 	struct drm_device *dev = connector->dev;
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	const struct nvif_notify_conn_rep_v0 *rep = notify->data;
-	const char *name = connector->name;
-	int ret;
 	bool plugged = (rep->mask != NVIF_NOTIFY_CONN_V0_UNPLUG);
 
 	if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
@@ -1156,31 +1168,9 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 		return NVIF_NOTIFY_KEEP;
 	}
 
-	ret = pm_runtime_get(drm->dev->dev);
-	if (ret == 0) {
-		/* We can't block here if there's a pending PM request
-		 * running, as we'll deadlock nouveau_display_fini() when it
-		 * calls nvif_put() on our nvif_notify struct. So, simply
-		 * defer the hotplug event until the device finishes resuming
-		 */
-		NV_DEBUG(drm, "Deferring HPD on %s until runtime resume\n",
-			 name);
-		schedule_work(&drm->hpd_work);
-
-		pm_runtime_put_noidle(drm->dev->dev);
-		return NVIF_NOTIFY_KEEP;
-	} else if (ret != 1 && ret != -EACCES) {
-		NV_WARN(drm, "HPD on %s dropped due to RPM failure: %d\n",
-			name, ret);
-		return NVIF_NOTIFY_DROP;
-	}
-
-	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", name);
-
-	drm_helper_hpd_irq_event(connector->dev);
+	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", connector->name);
+	nouveau_connector_hpd(connector);
 
-	pm_runtime_mark_last_busy(drm->dev->dev);
-	pm_runtime_put_autosuspend(drm->dev->dev);
 	return NVIF_NOTIFY_KEEP;
 }
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.h b/drivers/gpu/drm/nouveau/nouveau_connector.h
index d6de5cb8e2238..d0b859c4a80ea 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.h
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.h
@@ -187,6 +187,7 @@ nouveau_crtc_connector_get(struct nouveau_crtc *nv_crtc)
 
 struct drm_connector *
 nouveau_connector_create(struct drm_device *, const struct dcb_output *);
+void nouveau_connector_hpd(struct drm_connector *connector);
 
 extern int nouveau_tv_disable;
 extern int nouveau_ignorelid;
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index 13016769a194b..bceb48a2dfca6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -457,16 +457,70 @@ static struct nouveau_drm_prop_enum_list dither_depth[] = {
 	}                                                                      \
 } while(0)
 
+void
+nouveau_display_hpd_resume(struct drm_device *dev)
+{
+	struct nouveau_drm *drm = nouveau_drm(dev);
+
+	mutex_lock(&drm->hpd_lock);
+	drm->hpd_pending = ~0;
+	mutex_unlock(&drm->hpd_lock);
+
+	schedule_work(&drm->hpd_work);
+}
+
 static void
 nouveau_display_hpd_work(struct work_struct *work)
 {
 	struct nouveau_drm *drm = container_of(work, typeof(*drm), hpd_work);
+	struct drm_device *dev = drm->dev;
+	struct drm_connector *connector;
+	struct drm_connector_list_iter conn_iter;
+	u32 pending;
+	bool changed = false;
+
+	pm_runtime_get_sync(dev->dev);
 
-	pm_runtime_get_sync(drm->dev->dev);
+	mutex_lock(&drm->hpd_lock);
+	pending = drm->hpd_pending;
+	drm->hpd_pending = 0;
+	mutex_unlock(&drm->hpd_lock);
 
-	drm_helper_hpd_irq_event(drm->dev);
+	/* Nothing to do, exit early without updating the last busy counter */
+	if (!pending)
+		goto noop;
+
+	mutex_lock(&dev->mode_config.mutex);
+	drm_connector_list_iter_begin(dev, &conn_iter);
+
+	nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
+		enum drm_connector_status old_status = connector->status;
+		u64 old_epoch_counter = connector->epoch_counter;
+
+		if (!(pending & drm_connector_mask(connector)))
+			continue;
+
+		connector->status = drm_helper_probe_detect(connector, NULL,
+							    false);
+		if (old_epoch_counter == connector->epoch_counter)
+			continue;
+
+		changed = true;
+		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s (epoch counter %llu->%llu)\n",
+			    connector->base.id, connector->name,
+			    drm_get_connector_status_name(old_status),
+			    drm_get_connector_status_name(connector->status),
+			    old_epoch_counter, connector->epoch_counter);
+	}
+
+	drm_connector_list_iter_end(&conn_iter);
+	mutex_unlock(&dev->mode_config.mutex);
+
+	if (changed)
+		drm_kms_helper_hotplug_event(dev);
 
 	pm_runtime_mark_last_busy(drm->dev->dev);
+noop:
 	pm_runtime_put_sync(drm->dev->dev);
 }
 
@@ -490,12 +544,11 @@ nouveau_display_acpi_ntfy(struct notifier_block *nb, unsigned long val,
 				 */
 				pm_runtime_put_autosuspend(drm->dev->dev);
 			} else if (ret == 0) {
-				/* This may be the only indication we receive
-				 * of a connector hotplug on a runtime
-				 * suspended GPU, schedule hpd_work to check.
+				/* We've started resuming the GPU already, so
+				 * it will handle scheduling a full reprobe
+				 * itself
 				 */
 				NV_DEBUG(drm, "ACPI requested connector reprobe\n");
-				schedule_work(&drm->hpd_work);
 				pm_runtime_put_noidle(drm->dev->dev);
 			} else {
 				NV_WARN(drm, "Dropped ACPI reprobe event due to RPM error: %d\n",
@@ -686,6 +739,7 @@ nouveau_display_create(struct drm_device *dev)
 	}
 
 	INIT_WORK(&drm->hpd_work, nouveau_display_hpd_work);
+	mutex_init(&drm->hpd_lock);
 #ifdef CONFIG_ACPI
 	drm->acpi_nb.notifier_call = nouveau_display_acpi_ntfy;
 	register_acpi_notifier(&drm->acpi_nb);
@@ -705,9 +759,10 @@ void
 nouveau_display_destroy(struct drm_device *dev)
 {
 	struct nouveau_display *disp = nouveau_display(dev);
+	struct nouveau_drm *drm = nouveau_drm(dev);
 
 #ifdef CONFIG_ACPI
-	unregister_acpi_notifier(&nouveau_drm(dev)->acpi_nb);
+	unregister_acpi_notifier(&drm->acpi_nb);
 #endif
 
 	drm_kms_helper_poll_fini(dev);
@@ -719,6 +774,7 @@ nouveau_display_destroy(struct drm_device *dev)
 	nvif_disp_dtor(&disp->disp);
 
 	nouveau_drm(dev)->display = NULL;
+	mutex_destroy(&drm->hpd_lock);
 	kfree(disp);
 }
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.h b/drivers/gpu/drm/nouveau/nouveau_display.h
index 76ba93e01aff4..616c434270594 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.h
+++ b/drivers/gpu/drm/nouveau/nouveau_display.h
@@ -45,6 +45,7 @@ nouveau_display(struct drm_device *dev)
 int  nouveau_display_create(struct drm_device *dev);
 void nouveau_display_destroy(struct drm_device *dev);
 int  nouveau_display_init(struct drm_device *dev, bool resume, bool runtime);
+void nouveau_display_hpd_resume(struct drm_device *dev);
 void nouveau_display_fini(struct drm_device *dev, bool suspend, bool runtime);
 int  nouveau_display_suspend(struct drm_device *dev, bool runtime);
 void nouveau_display_resume(struct drm_device *dev, bool runtime);
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index a5934064a75ea..005750aeb6d4f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -165,7 +165,7 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 
 	if (mstm && mstm->is_mst) {
 		if (!nv50_mstm_service(drm, nv_connector, mstm))
-			schedule_work(&drm->hpd_work);
+			nouveau_connector_hpd(connector);
 	} else {
 		drm_dp_cec_irq(&nv_connector->aux);
 	}
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 22d246acc5e52..42fc5c813a9bb 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -953,7 +953,7 @@ nouveau_pmops_resume(struct device *dev)
 	ret = nouveau_do_resume(drm_dev, false);
 
 	/* Monitors may have been connected / disconnected during suspend */
-	schedule_work(&nouveau_drm(drm_dev)->hpd_work);
+	nouveau_display_hpd_resume(drm_dev);
 
 	return ret;
 }
@@ -1036,7 +1036,7 @@ nouveau_pmops_runtime_resume(struct device *dev)
 	drm_dev->switch_power_state = DRM_SWITCH_POWER_ON;
 
 	/* Monitors may have been connected / disconnected during suspend */
-	schedule_work(&nouveau_drm(drm_dev)->hpd_work);
+	nouveau_display_hpd_resume(drm_dev);
 
 	return ret;
 }
diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index f63ac72aa556f..73ebf5fba2fcd 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -198,6 +198,8 @@ struct nouveau_drm {
 	struct nvbios vbios;
 	struct nouveau_display *display;
 	struct work_struct hpd_work;
+	struct mutex hpd_lock;
+	u32 hpd_pending;
 	struct work_struct fbcon_work;
 	int fbcon_new_state;
 #ifdef CONFIG_ACPI
-- 
2.26.2

[PATCH v5 13/20] drm/i915/dp: Extract drm_dp_read_downstream_info()

[Lyude Paul]

We're going to be doing the same probing process in nouveau for
determining downstream DP port capabilities, so let's deduplicate the
work by moving i915's code for handling this into a shared helper:
drm_dp_read_downstream_info().

Note that when we do this, we also do make some functional changes while
we're at it:
* We always clear the downstream port info before trying to read it,
  just to make things easier for the caller
* We skip reading downstream port info if the DPCD indicates that we
  don't support downstream port info
* We only read as many bytes as needed for the reported number of
  downstream ports, no sense in reading the whole thing every time

v2:
* Fixup logic for calculating the downstream port length to account for
  the fact that downstream port caps can be either 1 byte or 4 bytes
  long. We can actually skip fixing the max_clock/max_bpc helpers here
  since they all check for DP_DETAILED_CAP_INFO_AVAILABLE anyway.
* Fix ret code check for drm_dp_dpcd_read
v5:
* Change name from drm_dp_downstream_read_info() to
  drm_dp_read_downstream_info()
* Also, add "See Also" sections for the various downstream info
  functions (drm_dp_read_downstream_info(), drm_dp_downstream_max_clock(),
  drm_dp_downstream_max_bpc())

Reviewed-by: Sean Paul <sean@poorly.run>
Signed-off-by: Lyude Paul <lyude@redhat.com>

squash! drm/i915/dp: Extract drm_dp_read_downstream_info()

Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 drivers/gpu/drm/drm_dp_helper.c         | 62 ++++++++++++++++++++++++-
 drivers/gpu/drm/i915/display/intel_dp.c | 14 +-----
 include/drm/drm_dp_helper.h             |  3 ++
 3 files changed, 65 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 4c21cf69dad5a..f3643894ad951 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -423,6 +423,56 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
 }
 EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
 
+static u8 drm_dp_downstream_port_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 port_count = dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_PORT_COUNT_MASK;
+
+	if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE && port_count > 4)
+		port_count = 4;
+
+	return port_count;
+}
+
+/**
+ * drm_dp_read_downstream_info() - read DPCD downstream port info if available
+ * @aux: DisplayPort AUX channel
+ * @dpcd: A cached copy of the port's DPCD
+ * @downstream_ports: buffer to store the downstream port info in
+ *
+ * See also:
+ * drm_dp_downstream_max_clock()
+ * drm_dp_downstream_max_bpc()
+ *
+ * Returns: 0 if either the downstream port info was read successfully or
+ * there was no downstream info to read, or a negative error code otherwise.
+ */
+int drm_dp_read_downstream_info(struct drm_dp_aux *aux,
+				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS])
+{
+	int ret;
+	u8 len;
+
+	memset(downstream_ports, 0, DP_MAX_DOWNSTREAM_PORTS);
+
+	/* No downstream info to read */
+	if (!drm_dp_is_branch(dpcd) ||
+	    dpcd[DP_DPCD_REV] < DP_DPCD_REV_10 ||
+	    !(dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT))
+		return 0;
+
+	len = drm_dp_downstream_port_count(dpcd);
+	if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE)
+		len *= 4;
+
+	ret = drm_dp_dpcd_read(aux, DP_DOWNSTREAM_PORT_0, downstream_ports, len);
+	if (ret < 0)
+		return ret;
+
+	return ret == len ? 0 : -EIO;
+}
+EXPORT_SYMBOL(drm_dp_read_downstream_info);
+
 /**
  * drm_dp_downstream_max_clock() - extract branch device max
  *                                 pixel rate for legacy VGA
@@ -431,7 +481,11 @@ EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
  * @dpcd: DisplayPort configuration data
  * @port_cap: port capabilities
  *
- * Returns max clock in kHz on success or 0 if max clock not defined
+ * See also:
+ * drm_dp_read_downstream_info()
+ * drm_dp_downstream_max_bpc()
+ *
+ * Returns: Max clock in kHz on success or 0 if max clock not defined
  */
 int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 				const u8 port_cap[4])
@@ -462,7 +516,11 @@ EXPORT_SYMBOL(drm_dp_downstream_max_clock);
  * @dpcd: DisplayPort configuration data
  * @port_cap: port capabilities
  *
- * Returns max bpc on success or 0 if max bpc not defined
+ * See also:
+ * drm_dp_read_downstream_info()
+ * drm_dp_downstream_max_clock()
+ *
+ * Returns: Max bpc on success or 0 if max bpc not defined
  */
 int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 			      const u8 port_cap[4])
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 4c7314b7a84e4..9c4b806af8c79 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4685,18 +4685,8 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 			return false;
 	}
 
-	if (!drm_dp_is_branch(intel_dp->dpcd))
-		return true; /* native DP sink */
-
-	if (intel_dp->dpcd[DP_DPCD_REV] == 0x10)
-		return true; /* no per-port downstream info */
-
-	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DOWNSTREAM_PORT_0,
-			     intel_dp->downstream_ports,
-			     DP_MAX_DOWNSTREAM_PORTS) < 0)
-		return false; /* downstream port status fetch failed */
-
-	return true;
+	return drm_dp_read_downstream_info(&intel_dp->aux, intel_dp->dpcd,
+					   intel_dp->downstream_ports) == 0;
 }
 
 static bool
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 5c28199248626..b8716b200666f 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1613,6 +1613,9 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
 				    u8 real_edid_checksum);
 
+int drm_dp_read_downstream_info(struct drm_dp_aux *aux,
+				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS]);
 int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 				const u8 port_cap[4]);
 int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
-- 
2.26.2

Re: [PATCH v5 13/20] drm/i915/dp: Extract drm_dp_read_downstream_info()

[Jani Nikula]

On Wed, 26 Aug 2020, Lyude Paul <lyude@redhat.com> wrote:
> We're going to be doing the same probing process in nouveau for
> determining downstream DP port capabilities, so let's deduplicate the
> work by moving i915's code for handling this into a shared helper:
> drm_dp_read_downstream_info().
>
> Note that when we do this, we also do make some functional changes while
> we're at it:
> * We always clear the downstream port info before trying to read it,
>   just to make things easier for the caller
> * We skip reading downstream port info if the DPCD indicates that we
>   don't support downstream port info
> * We only read as many bytes as needed for the reported number of
>   downstream ports, no sense in reading the whole thing every time
>
> v2:
> * Fixup logic for calculating the downstream port length to account for
>   the fact that downstream port caps can be either 1 byte or 4 bytes
>   long. We can actually skip fixing the max_clock/max_bpc helpers here
>   since they all check for DP_DETAILED_CAP_INFO_AVAILABLE anyway.
> * Fix ret code check for drm_dp_dpcd_read
> v5:
> * Change name from drm_dp_downstream_read_info() to
>   drm_dp_read_downstream_info()
> * Also, add "See Also" sections for the various downstream info
>   functions (drm_dp_read_downstream_info(), drm_dp_downstream_max_clock(),
>   drm_dp_downstream_max_bpc())
>
> Reviewed-by: Sean Paul <sean@poorly.run>
> Signed-off-by: Lyude Paul <lyude@redhat.com>
>
> squash! drm/i915/dp: Extract drm_dp_read_downstream_info()

Whoops!

>
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c         | 62 ++++++++++++++++++++++++-
>  drivers/gpu/drm/i915/display/intel_dp.c | 14 +-----
>  include/drm/drm_dp_helper.h             |  3 ++
>  3 files changed, 65 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 4c21cf69dad5a..f3643894ad951 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -423,6 +423,56 @@ bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
>  }
>  EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
>  
> +static u8 drm_dp_downstream_port_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> +{
> +	u8 port_count = dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_PORT_COUNT_MASK;
> +
> +	if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE && port_count > 4)
> +		port_count = 4;
> +
> +	return port_count;
> +}
> +
> +/**
> + * drm_dp_read_downstream_info() - read DPCD downstream port info if available
> + * @aux: DisplayPort AUX channel
> + * @dpcd: A cached copy of the port's DPCD
> + * @downstream_ports: buffer to store the downstream port info in
> + *
> + * See also:
> + * drm_dp_downstream_max_clock()
> + * drm_dp_downstream_max_bpc()
> + *
> + * Returns: 0 if either the downstream port info was read successfully or
> + * there was no downstream info to read, or a negative error code otherwise.
> + */
> +int drm_dp_read_downstream_info(struct drm_dp_aux *aux,
> +				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> +				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS])
> +{
> +	int ret;
> +	u8 len;
> +
> +	memset(downstream_ports, 0, DP_MAX_DOWNSTREAM_PORTS);
> +
> +	/* No downstream info to read */
> +	if (!drm_dp_is_branch(dpcd) ||
> +	    dpcd[DP_DPCD_REV] < DP_DPCD_REV_10 ||
> +	    !(dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT))
> +		return 0;

Generally I think stuff like this is easier and faster to read with
multiple if statements and early returns, but *shrug*.

I really hope we didn't have a reason to not check
DP_DWN_STRM_PORT_PRESENT here... there's been a lot of junk branch
devices in the past. Fingers crossed.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> +
> +	len = drm_dp_downstream_port_count(dpcd);
> +	if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE)
> +		len *= 4;
> +
> +	ret = drm_dp_dpcd_read(aux, DP_DOWNSTREAM_PORT_0, downstream_ports, len);
> +	if (ret < 0)
> +		return ret;
> +
> +	return ret == len ? 0 : -EIO;
> +}
> +EXPORT_SYMBOL(drm_dp_read_downstream_info);
> +
>  /**
>   * drm_dp_downstream_max_clock() - extract branch device max
>   *                                 pixel rate for legacy VGA
> @@ -431,7 +481,11 @@ EXPORT_SYMBOL(drm_dp_send_real_edid_checksum);
>   * @dpcd: DisplayPort configuration data
>   * @port_cap: port capabilities
>   *
> - * Returns max clock in kHz on success or 0 if max clock not defined
> + * See also:
> + * drm_dp_read_downstream_info()
> + * drm_dp_downstream_max_bpc()
> + *
> + * Returns: Max clock in kHz on success or 0 if max clock not defined
>   */
>  int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
>  				const u8 port_cap[4])
> @@ -462,7 +516,11 @@ EXPORT_SYMBOL(drm_dp_downstream_max_clock);
>   * @dpcd: DisplayPort configuration data
>   * @port_cap: port capabilities
>   *
> - * Returns max bpc on success or 0 if max bpc not defined
> + * See also:
> + * drm_dp_read_downstream_info()
> + * drm_dp_downstream_max_clock()
> + *
> + * Returns: Max bpc on success or 0 if max bpc not defined
>   */
>  int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
>  			      const u8 port_cap[4])
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 4c7314b7a84e4..9c4b806af8c79 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4685,18 +4685,8 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
>  			return false;
>  	}
>  
> -	if (!drm_dp_is_branch(intel_dp->dpcd))
> -		return true; /* native DP sink */
> -
> -	if (intel_dp->dpcd[DP_DPCD_REV] == 0x10)
> -		return true; /* no per-port downstream info */
> -
> -	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DOWNSTREAM_PORT_0,
> -			     intel_dp->downstream_ports,
> -			     DP_MAX_DOWNSTREAM_PORTS) < 0)
> -		return false; /* downstream port status fetch failed */
> -
> -	return true;
> +	return drm_dp_read_downstream_info(&intel_dp->aux, intel_dp->dpcd,
> +					   intel_dp->downstream_ports) == 0;
>  }
>  
>  static bool
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 5c28199248626..b8716b200666f 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1613,6 +1613,9 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
>  bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
>  				    u8 real_edid_checksum);
>  
> +int drm_dp_read_downstream_info(struct drm_dp_aux *aux,
> +				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> +				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS]);
>  int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
>  				const u8 port_cap[4]);
>  int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],

-- 
Jani Nikula, Intel Open Source Graphics Center

[PATCH v5 14/20] drm/nouveau/kms/nv50-: Use downstream DP clock limits for mode validation

[Lyude Paul]

This adds support for querying the maximum clock rate of a downstream
port on a DisplayPort connection. Generally, downstream ports refer to
active dongles which can have their own pixel clock limits.

Note as well, we also start marking the connector as disconnected if we
can't read the DPCD, since we wouldn't be able to do anything without
DPCD access anyway.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c   |  3 +++
 drivers/gpu/drm/nouveau/nouveau_dp.c      | 15 +++++++++++----
 drivers/gpu/drm/nouveau/nouveau_encoder.h |  1 +
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 8e1effb10425d..d2141ca16107b 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1258,7 +1258,10 @@ nv50_mstc_detect(struct drm_connector *connector,
 
 	ret = drm_dp_mst_detect_port(connector, ctx, mstc->port->mgr,
 				     mstc->port);
+	if (ret != connector_status_connected)
+		goto out;
 
+out:
 	pm_runtime_mark_last_busy(connector->dev->dev);
 	pm_runtime_put_autosuspend(connector->dev->dev);
 	return ret;
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 005750aeb6d4f..ad852e572cfec 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -61,6 +61,11 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 			mstm->can_mst = drm_dp_read_mst_cap(aux, dpcd);
 	}
 
+	ret = drm_dp_read_downstream_info(aux, dpcd,
+					  outp->dp.downstream_ports);
+	if (ret < 0)
+		return connector_status_disconnected;
+
 	return connector_status_connected;
 }
 
@@ -176,8 +181,6 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 /* TODO:
  * - Use the minimum possible BPC here, once we add support for the max bpc
  *   property.
- * - Validate the mode against downstream port caps (see
- *   drm_dp_downstream_max_clock())
  * - Validate against the DP caps advertised by the GPU (we don't check these
  *   yet)
  */
@@ -188,15 +191,19 @@ nv50_dp_mode_valid(struct drm_connector *connector,
 		   unsigned *out_clock)
 {
 	const unsigned min_clock = 25000;
-	unsigned max_clock, clock;
+	unsigned max_clock, ds_clock, clock;
 	enum drm_mode_status ret;
 
 	if (mode->flags & DRM_MODE_FLAG_INTERLACE && !outp->caps.dp_interlace)
 		return MODE_NO_INTERLACE;
 
 	max_clock = outp->dp.link_nr * outp->dp.link_bw;
-	clock = mode->clock * (connector->display_info.bpc * 3) / 10;
+	ds_clock = drm_dp_downstream_max_clock(outp->dp.dpcd,
+					       outp->dp.downstream_ports);
+	if (ds_clock)
+		max_clock = min(max_clock, ds_clock);
 
+	clock = mode->clock * (connector->display_info.bpc * 3) / 10;
 	ret = nouveau_conn_mode_clock_valid(mode, min_clock, max_clock,
 					    &clock);
 	if (out_clock)
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index eef4643f5f982..c1924a4529a7b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -72,6 +72,7 @@ struct nouveau_encoder {
 			struct mutex hpd_irq_lock;
 
 			u8 dpcd[DP_RECEIVER_CAP_SIZE];
+			u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
 			struct drm_dp_desc desc;
 		} dp;
 	};
-- 
2.26.2

Re: [Intel-gfx] [PATCH v5 14/20] drm/nouveau/kms/nv50-: Use downstream DP clock limits for mode validation

[Ville Syrjälä]

On Wed, Aug 26, 2020 at 02:24:50PM -0400, Lyude Paul wrote:
> This adds support for querying the maximum clock rate of a downstream
> port on a DisplayPort connection. Generally, downstream ports refer to
> active dongles which can have their own pixel clock limits.
> 
> Note as well, we also start marking the connector as disconnected if we
> can't read the DPCD, since we wouldn't be able to do anything without
> DPCD access anyway.
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
> ---
>  drivers/gpu/drm/nouveau/dispnv50/disp.c   |  3 +++
>  drivers/gpu/drm/nouveau/nouveau_dp.c      | 15 +++++++++++----
>  drivers/gpu/drm/nouveau/nouveau_encoder.h |  1 +
>  3 files changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> index 8e1effb10425d..d2141ca16107b 100644
> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> @@ -1258,7 +1258,10 @@ nv50_mstc_detect(struct drm_connector *connector,
>  
>  	ret = drm_dp_mst_detect_port(connector, ctx, mstc->port->mgr,
>  				     mstc->port);
> +	if (ret != connector_status_connected)
> +		goto out;
>  
> +out:
>  	pm_runtime_mark_last_busy(connector->dev->dev);
>  	pm_runtime_put_autosuspend(connector->dev->dev);
>  	return ret;
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
> index 005750aeb6d4f..ad852e572cfec 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dp.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
> @@ -61,6 +61,11 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
>  			mstm->can_mst = drm_dp_read_mst_cap(aux, dpcd);
>  	}
>  
> +	ret = drm_dp_read_downstream_info(aux, dpcd,
> +					  outp->dp.downstream_ports);
> +	if (ret < 0)
> +		return connector_status_disconnected;
> +
>  	return connector_status_connected;
>  }
>  
> @@ -176,8 +181,6 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
>  /* TODO:
>   * - Use the minimum possible BPC here, once we add support for the max bpc
>   *   property.
> - * - Validate the mode against downstream port caps (see
> - *   drm_dp_downstream_max_clock())
>   * - Validate against the DP caps advertised by the GPU (we don't check these
>   *   yet)
>   */
> @@ -188,15 +191,19 @@ nv50_dp_mode_valid(struct drm_connector *connector,
>  		   unsigned *out_clock)
>  {
>  	const unsigned min_clock = 25000;
> -	unsigned max_clock, clock;
> +	unsigned max_clock, ds_clock, clock;
>  	enum drm_mode_status ret;
>  
>  	if (mode->flags & DRM_MODE_FLAG_INTERLACE && !outp->caps.dp_interlace)
>  		return MODE_NO_INTERLACE;

I stumbled on this code when applying my big DFP series (sorry that
I forgot to read this while it was on the list).

Anyways, this code appears somewhat confused about the different
clocks.

>  
>  	max_clock = outp->dp.link_nr * outp->dp.link_bw;

That I presume is the max symbol rate of the link.

> -	clock = mode->clock * (connector->display_info.bpc * 3) / 10;
> +	ds_clock = drm_dp_downstream_max_clock(outp->dp.dpcd,
> +					       outp->dp.downstream_ports);

That is the maximum dotclock (also the max TMDS clock before my DFP
series landed) the DFP supports.

> +	if (ds_clock)
> +		max_clock = min(max_clock, ds_clock);

max() between the symbol rate and dotclock doesn't really
make sense. One is the amount of symbols (or data in other
words), the other is amount of pixels (which depending on
bpc can result in various amounts of symbols/data).

>  
> +	clock = mode->clock * (connector->display_info.bpc * 3) / 10;

I presume this trying to compute the symbol rate we require.
Due to the 8b/10b encoding each 10bit symbol carries 8 bits of
actual data, so the /10 should be /8. IIRC we had this same
bug in i915, but it was fixed years ago.

This is also calculating things based on display_info.bpc which
IIRC is the max bpc the display supports. Using the max may be
overly pessimistic in case a) the driver/hw doesn't even support
bpc that high, b) the driver can dynamically reduce the bpc in
order to fit the mode onto the link. In i915 we take the opposite
approach and just use the min bpc (==6) in mode_valid(). During
modeset we start from the max bpc and keep reducing it until
things fit.


So I suspect what you want here is something like:

max_clock = outp->dp.link_nr * outp->dp.link_bw;
clock = mode->clock * (connector->display_info.bpc * 3) / 8; // or maybe just use 6 for bpc
if (clock > max_clock)
	reurn CLOCK_HIGH;

ds_clock = drm_dp_downstream_max_dotclock();
if (ds_clock && mode->clock > ds_clock)
	return CLOCK_HIGH;

+ a bit more if you want to also deal with the TMDS
clock limits sensibly. That also requires some though
as to which bpc to use. In i915 we assume 8bpc when
calculating the TMDS clock since that's the minimum
DVI/HDMI supports.

-- 
Ville Syrjälä
Intel

[PATCH v5 15/20] drm/i915/dp: Extract drm_dp_read_sink_count_cap()

[Lyude Paul]

Since other drivers are also going to need to be aware of the sink count
in order to do proper dongle detection, we might as well steal i915's
DP_SINK_COUNT helpers and move them into DRM helpers so that other
dirvers can use them as well.

Note that this also starts using intel_dp_has_sink_count() in
intel_dp_detect_dpcd(), which is a functional change.

v5:
* Change name from drm_dp_has_sink_count() to
  drm_dp_read_sink_count_cap()

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Sean Paul <sean@poorly.run>
---
 drivers/gpu/drm/drm_dp_helper.c         | 22 ++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c | 21 ++++++++++++---------
 include/drm/drm_dp_helper.h             |  8 +++++++-
 3 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index f3643894ad951..65ff21ae0c271 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -726,6 +726,28 @@ void drm_dp_set_subconnector_property(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_dp_set_subconnector_property);
 
+/**
+ * drm_dp_read_sink_count_cap() - Check whether a given connector has a valid sink
+ * count
+ * @connector: The DRM connector to check
+ * @dpcd: A cached copy of the connector's DPCD RX capabilities
+ * @desc: A cached copy of the connector's DP descriptor
+ *
+ * Returns: %True if the (e)DP connector has a valid sink count that should
+ * be probed, %false otherwise.
+ */
+bool drm_dp_read_sink_count_cap(struct drm_connector *connector,
+				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+				const struct drm_dp_desc *desc)
+{
+	/* Some eDP panels don't set a valid value for the sink count */
+	return connector->connector_type != DRM_MODE_CONNECTOR_eDP &&
+		dpcd[DP_DPCD_REV] >= DP_DPCD_REV_11 &&
+		dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT &&
+		!drm_dp_has_quirk(desc, 0, DP_DPCD_QUIRK_NO_SINK_COUNT);
+}
+EXPORT_SYMBOL(drm_dp_read_sink_count_cap);
+
 /*
  * I2C-over-AUX implementation
  */
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 9c4b806af8c79..38318ae935f88 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4634,6 +4634,16 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
 	return true;
 }
 
+static bool
+intel_dp_has_sink_count(struct intel_dp *intel_dp)
+{
+	if (!intel_dp->attached_connector)
+		return false;
+
+	return drm_dp_read_sink_count_cap(&intel_dp->attached_connector->base,
+					  intel_dp->dpcd,
+					  &intel_dp->desc);
+}
 
 static bool
 intel_dp_get_dpcd(struct intel_dp *intel_dp)
@@ -4653,13 +4663,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 		intel_dp_set_common_rates(intel_dp);
 	}
 
-	/*
-	 * Some eDP panels do not set a valid value for sink count, that is why
-	 * it don't care about read it here and in intel_edp_init_dpcd().
-	 */
-	if (!intel_dp_is_edp(intel_dp) &&
-	    !drm_dp_has_quirk(&intel_dp->desc, 0,
-			      DP_DPCD_QUIRK_NO_SINK_COUNT)) {
+	if (intel_dp_has_sink_count(intel_dp)) {
 		u8 count;
 		ssize_t r;
 
@@ -5939,9 +5943,8 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
 		return connector_status_connected;
 
 	/* If we're HPD-aware, SINK_COUNT changes dynamically */
-	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
+	if (intel_dp_has_sink_count(intel_dp) &&
 	    intel_dp->downstream_ports[0] & DP_DS_PORT_HPD) {
-
 		return intel_dp->sink_count ?
 		connector_status_connected : connector_status_disconnected;
 	}
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index b8716b200666f..4c56ce4dc54fc 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1631,6 +1631,11 @@ void drm_dp_set_subconnector_property(struct drm_connector *connector,
 				      const u8 *dpcd,
 				      const u8 port_cap[4]);
 
+struct drm_dp_desc;
+bool drm_dp_read_sink_count_cap(struct drm_connector *connector,
+				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+				const struct drm_dp_desc *desc);
+
 void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
 void drm_dp_aux_init(struct drm_dp_aux *aux);
 int drm_dp_aux_register(struct drm_dp_aux *aux);
@@ -1689,7 +1694,8 @@ enum drm_dp_quirk {
 	 * @DP_DPCD_QUIRK_NO_SINK_COUNT:
 	 *
 	 * The device does not set SINK_COUNT to a non-zero value.
-	 * The driver should ignore SINK_COUNT during detection.
+	 * The driver should ignore SINK_COUNT during detection. Note that
+	 * drm_dp_read_sink_count_cap() automatically checks for this quirk.
 	 */
 	DP_DPCD_QUIRK_NO_SINK_COUNT,
 	/**
-- 
2.26.2

[PATCH v5 16/20] drm/i915/dp: Extract drm_dp_read_sink_count()

[Lyude Paul]

And of course, we'll also need to read the sink count from other drivers
as well if we're checking whether or not it's supported. So, let's
extract the code for this into another helper.

v2:
* Fix drm_dp_dpcd_readb() ret check
* Add back comment and move back sink_count assignment in intel_dp_get_dpcd()
v5:
* Change name from drm_dp_get_sink_count() to drm_dp_read_sink_count()
* Also, add "See also:" section to kdocs

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Sean Paul <sean@poorly.run>
---
 drivers/gpu/drm/drm_dp_helper.c         | 26 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c | 11 +++++------
 include/drm/drm_dp_helper.h             |  1 +
 3 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 65ff21ae0c271..46d88ef4f59ac 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -733,6 +733,8 @@ EXPORT_SYMBOL(drm_dp_set_subconnector_property);
  * @dpcd: A cached copy of the connector's DPCD RX capabilities
  * @desc: A cached copy of the connector's DP descriptor
  *
+ * See also: drm_dp_read_sink_count()
+ *
  * Returns: %True if the (e)DP connector has a valid sink count that should
  * be probed, %false otherwise.
  */
@@ -748,6 +750,30 @@ bool drm_dp_read_sink_count_cap(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_dp_read_sink_count_cap);
 
+/**
+ * drm_dp_read_sink_count() - Retrieve the sink count for a given sink
+ * @aux: The DP AUX channel to use
+ *
+ * See also: drm_dp_read_sink_count_cap()
+ *
+ * Returns: The current sink count reported by @aux, or a negative error code
+ * otherwise.
+ */
+int drm_dp_read_sink_count(struct drm_dp_aux *aux)
+{
+	u8 count;
+	int ret;
+
+	ret = drm_dp_dpcd_readb(aux, DP_SINK_COUNT, &count);
+	if (ret < 0)
+		return ret;
+	if (ret != 1)
+		return -EIO;
+
+	return DP_GET_SINK_COUNT(count);
+}
+EXPORT_SYMBOL(drm_dp_read_sink_count);
+
 /*
  * I2C-over-AUX implementation
  */
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 38318ae935f88..0de94fc6289be 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4648,6 +4648,8 @@ intel_dp_has_sink_count(struct intel_dp *intel_dp)
 static bool
 intel_dp_get_dpcd(struct intel_dp *intel_dp)
 {
+	int ret;
+
 	if (!intel_dp_read_dpcd(intel_dp))
 		return false;
 
@@ -4664,11 +4666,8 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 	}
 
 	if (intel_dp_has_sink_count(intel_dp)) {
-		u8 count;
-		ssize_t r;
-
-		r = drm_dp_dpcd_readb(&intel_dp->aux, DP_SINK_COUNT, &count);
-		if (r < 1)
+		ret = drm_dp_read_sink_count(&intel_dp->aux);
+		if (ret < 0)
 			return false;
 
 		/*
@@ -4676,7 +4675,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 		 * a member variable in intel_dp will track any changes
 		 * between short pulse interrupts.
 		 */
-		intel_dp->sink_count = DP_GET_SINK_COUNT(count);
+		intel_dp->sink_count = ret;
 
 		/*
 		 * SINK_COUNT == 0 and DOWNSTREAM_PORT_PRESENT == 1 implies that
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 4c56ce4dc54fc..bc5cb8c503fbc 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1635,6 +1635,7 @@ struct drm_dp_desc;
 bool drm_dp_read_sink_count_cap(struct drm_connector *connector,
 				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 				const struct drm_dp_desc *desc);
+int drm_dp_read_sink_count(struct drm_dp_aux *aux);
 
 void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
 void drm_dp_aux_init(struct drm_dp_aux *aux);
-- 
2.26.2

[PATCH v5 17/20] drm/nouveau/kms/nv50-: Add support for DP_SINK_COUNT

[Lyude Paul]

This is another bit that we never implemented for nouveau: dongle
detection. When a "dongle", e.g. an active display adaptor, is hooked up
to the system and causes an HPD to be fired, we don't actually know
whether or not there's anything plugged into the dongle without checking
the sink count. As a result, plugging in a dongle without anything
plugged into it currently results in a bogus EDID retrieval error in the kernel log.

Additionally, most dongles won't send another long HPD signal if the
user suddenly plugs something in, they'll only send a short HPD IRQ with
the expectation that the source will check the sink count and reprobe
the connector if it's changed - something we don't actually do. As a
result, nothing will happen if the user plugs the dongle in before
plugging something into the dongle.

So, let's fix this by checking the sink count in both
nouveau_dp_probe_dpcd() and nouveau_dp_irq(), and reprobing the
connector if things change.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c      | 53 ++++++++++++++++++++---
 drivers/gpu/drm/nouveau/nouveau_encoder.h |  2 +
 2 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index ad852e572cfec..59be357b17e00 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -36,12 +36,21 @@ MODULE_PARM_DESC(mst, "Enable DisplayPort multi-stream (default: enabled)");
 static int nouveau_mst = 1;
 module_param_named(mst, nouveau_mst, int, 0400);
 
+static bool
+nouveau_dp_has_sink_count(struct drm_connector *connector,
+			  struct nouveau_encoder *outp)
+{
+	return drm_dp_read_sink_count_cap(connector, outp->dp.dpcd, &outp->dp.desc);
+}
+
 static enum drm_connector_status
 nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 		      struct nouveau_encoder *outp)
 {
+	struct drm_connector *connector = &nv_connector->base;
 	struct drm_dp_aux *aux = &nv_connector->aux;
 	struct nv50_mstm *mstm = NULL;
+	enum drm_connector_status status = connector_status_disconnected;
 	int ret;
 	u8 *dpcd = outp->dp.dpcd;
 
@@ -50,9 +59,9 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 		ret = drm_dp_read_desc(aux, &outp->dp.desc,
 				       drm_dp_is_branch(dpcd));
 		if (ret < 0)
-			return connector_status_disconnected;
+			goto out;
 	} else {
-		return connector_status_disconnected;
+		goto out;
 	}
 
 	if (nouveau_mst) {
@@ -61,12 +70,33 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 			mstm->can_mst = drm_dp_read_mst_cap(aux, dpcd);
 	}
 
+	if (nouveau_dp_has_sink_count(connector, outp)) {
+		ret = drm_dp_read_sink_count(aux);
+		if (ret < 0)
+			goto out;
+
+		outp->dp.sink_count = ret;
+
+		/*
+		 * Dongle connected, but no display. Don't bother reading
+		 * downstream port info
+		 */
+		if (!outp->dp.sink_count)
+			return connector_status_disconnected;
+	}
+
 	ret = drm_dp_read_downstream_info(aux, dpcd,
 					  outp->dp.downstream_ports);
 	if (ret < 0)
-		return connector_status_disconnected;
+		goto out;
 
-	return connector_status_connected;
+	status = connector_status_connected;
+out:
+	if (status != connector_status_connected) {
+		/* Clear any cached info */
+		outp->dp.sink_count = 0;
+	}
+	return status;
 }
 
 int
@@ -159,6 +189,8 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 	struct drm_connector *connector = &nv_connector->base;
 	struct nouveau_encoder *outp = find_encoder(connector, DCB_OUTPUT_DP);
 	struct nv50_mstm *mstm;
+	int ret;
+	bool send_hpd = false;
 
 	if (!outp)
 		return;
@@ -170,12 +202,23 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 
 	if (mstm && mstm->is_mst) {
 		if (!nv50_mstm_service(drm, nv_connector, mstm))
-			nouveau_connector_hpd(connector);
+			send_hpd = true;
 	} else {
 		drm_dp_cec_irq(&nv_connector->aux);
+
+		if (nouveau_dp_has_sink_count(connector, outp)) {
+			ret = drm_dp_read_sink_count(&nv_connector->aux);
+			if (ret != outp->dp.sink_count)
+				send_hpd = true;
+			if (ret >= 0)
+				outp->dp.sink_count = ret;
+		}
 	}
 
 	mutex_unlock(&outp->dp.hpd_irq_lock);
+
+	if (send_hpd)
+		nouveau_connector_hpd(connector);
 }
 
 /* TODO:
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index c1924a4529a7b..21937f1c7dd90 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -74,6 +74,8 @@ struct nouveau_encoder {
 			u8 dpcd[DP_RECEIVER_CAP_SIZE];
 			u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
 			struct drm_dp_desc desc;
+
+			u8 sink_count;
 		} dp;
 	};
 
-- 
2.26.2

[PATCH v5 18/20] drm/nouveau/kms: Don't change EDID when it hasn't actually changed

[Lyude Paul]

Currently in nouveau_connector_ddc_detect() and
nouveau_connector_detect_lvds(), we start the connector probing process
by releasing the previous EDID and informing DRM of the change. However,
since commit 5186421cbfe2 ("drm: Introduce epoch counter to
drm_connector") drm_connector_update_edid_property() actually checks
whether the new EDID we've specified is different from the previous one,
and updates the connector's epoch accordingly if it is. But, because we
always set the EDID to NULL first in nouveau_connector_ddc_detect() and
nouveau_connector_detect_lvds() we end up making DRM think that the EDID
changes every single time we do a connector probe - which isn't needed.

So, let's fix this by not clearing the EDID at the start of the
connector probing process, and instead simply changing or removing it
once near the end of the probing process. This will help prevent us from
sending unneeded hotplug events to userspace when nothing has actually
changed.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 54 ++++++++++-----------
 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 637e91594fbe8..49dd0cbc332ff 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -528,6 +528,17 @@ nouveau_connector_set_encoder(struct drm_connector *connector,
 	}
 }
 
+static void
+nouveau_connector_set_edid(struct nouveau_connector *nv_connector,
+			   struct edid *edid)
+{
+	struct edid *old_edid = nv_connector->edid;
+
+	drm_connector_update_edid_property(&nv_connector->base, edid);
+	kfree(old_edid);
+	nv_connector->edid = edid;
+}
+
 static enum drm_connector_status
 nouveau_connector_detect(struct drm_connector *connector, bool force)
 {
@@ -541,13 +552,6 @@ nouveau_connector_detect(struct drm_connector *connector, bool force)
 	int ret;
 	enum drm_connector_status conn_status = connector_status_disconnected;
 
-	/* Cleanup the previous EDID block. */
-	if (nv_connector->edid) {
-		drm_connector_update_edid_property(connector, NULL);
-		kfree(nv_connector->edid);
-		nv_connector->edid = NULL;
-	}
-
 	/* Outputs are only polled while runtime active, so resuming the
 	 * device here is unnecessary (and would deadlock upon runtime suspend
 	 * because it waits for polling to finish). We do however, want to
@@ -560,22 +564,23 @@ nouveau_connector_detect(struct drm_connector *connector, bool force)
 		ret = pm_runtime_get_sync(dev->dev);
 		if (ret < 0 && ret != -EACCES) {
 			pm_runtime_put_autosuspend(dev->dev);
+			nouveau_connector_set_edid(nv_connector, NULL);
 			return conn_status;
 		}
 	}
 
 	nv_encoder = nouveau_connector_ddc_detect(connector);
 	if (nv_encoder && (i2c = nv_encoder->i2c) != NULL) {
+		struct edid *new_edid;
+
 		if ((vga_switcheroo_handler_flags() &
 		     VGA_SWITCHEROO_CAN_SWITCH_DDC) &&
 		    nv_connector->type == DCB_CONNECTOR_LVDS)
-			nv_connector->edid = drm_get_edid_switcheroo(connector,
-								     i2c);
+			new_edid = drm_get_edid_switcheroo(connector, i2c);
 		else
-			nv_connector->edid = drm_get_edid(connector, i2c);
+			new_edid = drm_get_edid(connector, i2c);
 
-		drm_connector_update_edid_property(connector,
-							nv_connector->edid);
+		nouveau_connector_set_edid(nv_connector, new_edid);
 		if (!nv_connector->edid) {
 			NV_ERROR(drm, "DDC responded, but no EDID for %s\n",
 				 connector->name);
@@ -609,6 +614,8 @@ nouveau_connector_detect(struct drm_connector *connector, bool force)
 		conn_status = connector_status_connected;
 		drm_dp_cec_set_edid(&nv_connector->aux, nv_connector->edid);
 		goto out;
+	} else {
+		nouveau_connector_set_edid(nv_connector, NULL);
 	}
 
 	nv_encoder = nouveau_connector_of_detect(connector);
@@ -652,18 +659,12 @@ nouveau_connector_detect_lvds(struct drm_connector *connector, bool force)
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct nouveau_connector *nv_connector = nouveau_connector(connector);
 	struct nouveau_encoder *nv_encoder = NULL;
+	struct edid *edid = NULL;
 	enum drm_connector_status status = connector_status_disconnected;
 
-	/* Cleanup the previous EDID block. */
-	if (nv_connector->edid) {
-		drm_connector_update_edid_property(connector, NULL);
-		kfree(nv_connector->edid);
-		nv_connector->edid = NULL;
-	}
-
 	nv_encoder = find_encoder(connector, DCB_OUTPUT_LVDS);
 	if (!nv_encoder)
-		return connector_status_disconnected;
+		goto out;
 
 	/* Try retrieving EDID via DDC */
 	if (!drm->vbios.fp_no_ddc) {
@@ -682,7 +683,8 @@ nouveau_connector_detect_lvds(struct drm_connector *connector, bool force)
 	 * valid - it's not (rh#613284)
 	 */
 	if (nv_encoder->dcb->lvdsconf.use_acpi_for_edid) {
-		if ((nv_connector->edid = nouveau_acpi_edid(dev, connector))) {
+		edid = nouveau_acpi_edid(dev, connector);
+		if (edid) {
 			status = connector_status_connected;
 			goto out;
 		}
@@ -702,12 +704,10 @@ nouveau_connector_detect_lvds(struct drm_connector *connector, bool force)
 	 * stored for the panel stored in them.
 	 */
 	if (!drm->vbios.fp_no_ddc) {
-		struct edid *edid =
-			(struct edid *)nouveau_bios_embedded_edid(dev);
+		edid = (struct edid *)nouveau_bios_embedded_edid(dev);
 		if (edid) {
-			nv_connector->edid =
-					kmemdup(edid, EDID_LENGTH, GFP_KERNEL);
-			if (nv_connector->edid)
+			edid = kmemdup(edid, EDID_LENGTH, GFP_KERNEL);
+			if (edid)
 				status = connector_status_connected;
 		}
 	}
@@ -720,7 +720,7 @@ nouveau_connector_detect_lvds(struct drm_connector *connector, bool force)
 		status = connector_status_unknown;
 #endif
 
-	drm_connector_update_edid_property(connector, nv_connector->edid);
+	nouveau_connector_set_edid(nv_connector, edid);
 	nouveau_connector_set_encoder(connector, nv_encoder);
 	return status;
 }
-- 
2.26.2

[PATCH v5 19/20] drm/i915/dp: Extract drm_dp_read_dpcd_caps()

[Lyude Paul]

Since DP 1.3, it's been possible for DP receivers to specify an
additional set of DPCD capabilities, which can take precedence over the
capabilities reported at DP_DPCD_REV.

Basically any device supporting DP is going to need to read these in an
identical manner, in particular nouveau, so let's go ahead and just move
this code out of i915 into a shared DRM DP helper that we can use in
other drivers.

v2:
* Remove redundant dpcd[DP_DPCD_REV] == 0 check
* Fix drm_dp_dpcd_read() ret checks

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Sean Paul <sean@poorly.run>
---
 drivers/gpu/drm/drm_dp_helper.c             | 77 +++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c     | 60 +---------------
 drivers/gpu/drm/i915/display/intel_dp.h     |  1 -
 drivers/gpu/drm/i915/display/intel_lspcon.c |  2 +-
 include/drm/drm_dp_helper.h                 |  3 +
 5 files changed, 83 insertions(+), 60 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 46d88ef4f59ac..9ca88e6c78820 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -433,6 +433,83 @@ static u8 drm_dp_downstream_port_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 	return port_count;
 }
 
+static int drm_dp_read_extended_dpcd_caps(struct drm_dp_aux *aux,
+					  u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 dpcd_ext[6];
+	int ret;
+
+	/*
+	 * Prior to DP1.3 the bit represented by
+	 * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved.
+	 * If it is set DP_DPCD_REV at 0000h could be at a value less than
+	 * the true capability of the panel. The only way to check is to
+	 * then compare 0000h and 2200h.
+	 */
+	if (!(dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
+	      DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT))
+		return 0;
+
+	ret = drm_dp_dpcd_read(aux, DP_DP13_DPCD_REV, &dpcd_ext,
+			       sizeof(dpcd_ext));
+	if (ret < 0)
+		return ret;
+	if (ret != sizeof(dpcd_ext))
+		return -EIO;
+
+	if (dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) {
+		DRM_DEBUG_KMS("%s: Extended DPCD rev less than base DPCD rev (%d > %d)\n",
+			      aux->name, dpcd[DP_DPCD_REV],
+			      dpcd_ext[DP_DPCD_REV]);
+		return 0;
+	}
+
+	if (!memcmp(dpcd, dpcd_ext, sizeof(dpcd_ext)))
+		return 0;
+
+	DRM_DEBUG_KMS("%s: Base DPCD: %*ph\n",
+		      aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
+
+	memcpy(dpcd, dpcd_ext, sizeof(dpcd_ext));
+
+	return 0;
+}
+
+/**
+ * drm_dp_read_dpcd_caps() - read DPCD caps and extended DPCD caps if
+ * available
+ * @aux: DisplayPort AUX channel
+ * @dpcd: Buffer to store the resulting DPCD in
+ *
+ * Attempts to read the base DPCD caps for @aux. Additionally, this function
+ * checks for and reads the extended DPRX caps (%DP_DP13_DPCD_REV) if
+ * present.
+ *
+ * Returns: %0 if the DPCD was read successfully, negative error code
+ * otherwise.
+ */
+int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
+			  u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	int ret;
+
+	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
+	if (ret < 0)
+		return ret;
+	if (ret != DP_RECEIVER_CAP_SIZE || dpcd[DP_DPCD_REV] == 0)
+		return -EIO;
+
+	ret = drm_dp_read_extended_dpcd_caps(aux, dpcd);
+	if (ret < 0)
+		return ret;
+
+	DRM_DEBUG_KMS("%s: DPCD: %*ph\n",
+		      aux->name, DP_RECEIVER_CAP_SIZE, dpcd);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_read_dpcd_caps);
+
 /**
  * drm_dp_read_downstream_info() - read DPCD downstream port info if available
  * @aux: DisplayPort AUX channel
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 0de94fc6289be..284b15f845926 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4449,62 +4449,6 @@ intel_dp_link_down(struct intel_encoder *encoder,
 	}
 }
 
-static void
-intel_dp_extended_receiver_capabilities(struct intel_dp *intel_dp)
-{
-	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
-	u8 dpcd_ext[6];
-
-	/*
-	 * Prior to DP1.3 the bit represented by
-	 * DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT was reserved.
-	 * if it is set DP_DPCD_REV at 0000h could be at a value less than
-	 * the true capability of the panel. The only way to check is to
-	 * then compare 0000h and 2200h.
-	 */
-	if (!(intel_dp->dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
-	      DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT))
-		return;
-
-	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DP13_DPCD_REV,
-			     &dpcd_ext, sizeof(dpcd_ext)) != sizeof(dpcd_ext)) {
-		drm_err(&i915->drm,
-			"DPCD failed read at extended capabilities\n");
-		return;
-	}
-
-	if (intel_dp->dpcd[DP_DPCD_REV] > dpcd_ext[DP_DPCD_REV]) {
-		drm_dbg_kms(&i915->drm,
-			    "DPCD extended DPCD rev less than base DPCD rev\n");
-		return;
-	}
-
-	if (!memcmp(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext)))
-		return;
-
-	drm_dbg_kms(&i915->drm, "Base DPCD: %*ph\n",
-		    (int)sizeof(intel_dp->dpcd), intel_dp->dpcd);
-
-	memcpy(intel_dp->dpcd, dpcd_ext, sizeof(dpcd_ext));
-}
-
-bool
-intel_dp_read_dpcd(struct intel_dp *intel_dp)
-{
-	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
-
-	if (drm_dp_dpcd_read(&intel_dp->aux, 0x000, intel_dp->dpcd,
-			     sizeof(intel_dp->dpcd)) < 0)
-		return false; /* aux transfer failed */
-
-	intel_dp_extended_receiver_capabilities(intel_dp);
-
-	drm_dbg_kms(&i915->drm, "DPCD: %*ph\n", (int)sizeof(intel_dp->dpcd),
-		    intel_dp->dpcd);
-
-	return intel_dp->dpcd[DP_DPCD_REV] != 0;
-}
-
 bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
 {
 	u8 dprx = 0;
@@ -4563,7 +4507,7 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
 	/* this function is meant to be called only once */
 	drm_WARN_ON(&dev_priv->drm, intel_dp->dpcd[DP_DPCD_REV] != 0);
 
-	if (!intel_dp_read_dpcd(intel_dp))
+	if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd) != 0)
 		return false;
 
 	drm_dp_read_desc(&intel_dp->aux, &intel_dp->desc,
@@ -4650,7 +4594,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 {
 	int ret;
 
-	if (!intel_dp_read_dpcd(intel_dp))
+	if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd))
 		return false;
 
 	/*
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index b901ab850cbd9..0a3af3410d52e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -99,7 +99,6 @@ bool intel_dp_source_supports_hbr3(struct intel_dp *intel_dp);
 bool
 intel_dp_get_link_status(struct intel_dp *intel_dp, u8 *link_status);
 
-bool intel_dp_read_dpcd(struct intel_dp *intel_dp);
 bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp);
 int intel_dp_link_required(int pixel_clock, int bpp);
 int intel_dp_max_data_rate(int max_link_clock, int max_lanes);
diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c b/drivers/gpu/drm/i915/display/intel_lspcon.c
index b781bf4696443..dc1b35559afdf 100644
--- a/drivers/gpu/drm/i915/display/intel_lspcon.c
+++ b/drivers/gpu/drm/i915/display/intel_lspcon.c
@@ -571,7 +571,7 @@ bool lspcon_init(struct intel_digital_port *dig_port)
 		return false;
 	}
 
-	if (!intel_dp_read_dpcd(dp)) {
+	if (drm_dp_read_dpcd_caps(&dp->aux, dp->dpcd) != 0) {
 		DRM_ERROR("LSPCON DPCD read failed\n");
 		return false;
 	}
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index bc5cb8c503fbc..85513eeb21966 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1607,6 +1607,9 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux,
 	return drm_dp_dpcd_write(aux, offset, &value, 1);
 }
 
+int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
+			  u8 dpcd[DP_RECEIVER_CAP_SIZE]);
+
 int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 				 u8 status[DP_LINK_STATUS_SIZE]);
 
-- 
2.26.2

[PATCH v5 20/20] drm/nouveau/kms: Start using drm_dp_read_dpcd_caps()

[Lyude Paul]

Now that we've extracted i915's code for reading both the normal DPCD
caps and extended DPCD caps into a shared helper, let's start using this
in nouveau to enable us to start checking extended DPCD caps for free.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_dp.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index 59be357b17e00..810bf69565683 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -54,15 +54,13 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 	int ret;
 	u8 *dpcd = outp->dp.dpcd;
 
-	ret = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, DP_RECEIVER_CAP_SIZE);
-	if (ret == DP_RECEIVER_CAP_SIZE && dpcd[DP_DPCD_REV]) {
-		ret = drm_dp_read_desc(aux, &outp->dp.desc,
-				       drm_dp_is_branch(dpcd));
-		if (ret < 0)
-			goto out;
-	} else {
+	ret = drm_dp_read_dpcd_caps(aux, dpcd);
+	if (ret < 0)
+		goto out;
+
+	ret = drm_dp_read_desc(aux, &outp->dp.desc, drm_dp_is_branch(dpcd));
+	if (ret < 0)
 		goto out;
-	}
 
 	if (nouveau_mst) {
 		mstm = outp->dp.mstm;
-- 
2.26.2