[PATCH v3 00/26] device link, bridge supplier <-> drm device

[PATCH v3 00/26] device link, bridge supplier <-> drm device

[Peter Rosin]

Hi!

It was noted by Russell King [1] that bridges (not using components)
might disappear unexpectedly if the owner of the bridge was unbound.
Jyri Sarha had previously noted the same thing with panels [2]. Jyri
came up with using device links to resolve the panel issue, which
was also my (independent) reaction to the note from Russell.

This series builds up to the addition of that link in the last
patch, but in my opinion the other 25 patches do have merit on their
own.

The last patch needs testing, while the others look trivial. Jyri, are
you able to test? That said, I might have missed some subtlety.

Oh, and the reason I'm pushing this is of course so that the issue
noted by Russell in [1] is addressed which in turn means that the
tda998x bridge driver can be patched according to that series without
objection (hopefully) and then used from the atmel-hlcdc driver (and
other drivers that are not componentized).

Changes since v2    https://lkml.org/lkml/2018/5/4/443

- Russell King spells his name this way. Sorry!
- Add review tag from Andrzej Hajda (patches 1, 25 and 26).
- Add ack tag from Daniel Vetter (patches 1, 24, 25 and 26).
- Mention the interaction with the rockchip_lvds driver in the
  commit message for patch 1.
- Change the comment for the new @link member in patch 26, so that a
  symmetric relationchip between cunsumer/supplier isn't implied.

Changes since v1    https://lkml.org/lkml/2018/4/26/1018

- rename .owner to .odev to not get mixed up with the module owner.
- added patches for new recent drivers thc63lvd1024 and cdns-dsi
- fix for problem in the rockchip_lvds driver reported by 0day
- added a WARN in drm_bridge_add if there is no .odev owner device

Cheers,
Peter

[1] https://lkml.org/lkml/2018/4/23/769
[2] https://www.spinics.net/lists/dri-devel/msg174275.html

Peter Rosin (26):
  drm/bridge: allow optionally specifying an owner .odev device
  drm/bridge: adv7511: provide an owner .odev device
  drm/bridge/analogix: core: specify the owner .odev of the bridge
  drm/bridge: analogix-anx78xx: provide an owner .odev device
  drm/bridge: cdns-dsi: provide an owner .odev device
  drm/bridge: vga-dac: provide an owner .odev device
  drm/bridge: lvds-encoder: provide an owner .odev device
  drm/bridge: megachips-stdpxxxx-ge-b850v3-fw: provide an owner .odev
    device
  drm/bridge: nxp-ptn3460: provide an owner .odev device
  drm/bridge: panel: provide an owner .odev device
  drm/bridge: ps8622: provide an owner .odev device
  drm/bridge: sii902x: provide an owner .odev device
  drm/bridge: sii9234: provide an owner .odev device
  drm/bridge: sii8620: provide an owner .odev device
  drm/bridge: synopsys: provide an owner .odev device for the bridges
  drm/bridge: tc358767: provide an owner .odev device
  drm/bridge: thc63lvd1024: provide an owner .odev device
  drm/bridge: ti-tfp410: provide an owner .odev device
  drm/exynos: mic: provide an owner .odev device for the bridge
  drm/mediatek: hdmi: provide an owner .odev device for the bridge
  drm/msm: specify the owner .odev of the bridges
  drm/rcar-du: lvds: provide an owner .odev device for the bridge
  drm/sti: provide an owner .odev device for the bridges
  drm/bridge: remove the .of_node member
  drm/bridge: require the owner .odev to be filled in on
    drm_bridge_add/attach
  drm/bridge: establish a link between the bridge supplier and consumer

 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c       |  2 +-
 drivers/gpu/drm/bridge/analogix-anx78xx.c          |  5 +----
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c |  1 +
 drivers/gpu/drm/bridge/cdns-dsi.c                  |  2 +-
 drivers/gpu/drm/bridge/dumb-vga-dac.c              |  2 +-
 drivers/gpu/drm/bridge/lvds-encoder.c              |  2 +-
 .../drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c   |  2 +-
 drivers/gpu/drm/bridge/nxp-ptn3460.c               |  2 +-
 drivers/gpu/drm/bridge/panel.c                     |  4 +---
 drivers/gpu/drm/bridge/parade-ps8622.c             |  2 +-
 drivers/gpu/drm/bridge/sii902x.c                   |  2 +-
 drivers/gpu/drm/bridge/sii9234.c                   |  2 +-
 drivers/gpu/drm/bridge/sil-sii8620.c               |  2 +-
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c          |  4 +---
 drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c      |  4 +---
 drivers/gpu/drm/bridge/tc358767.c                  |  2 +-
 drivers/gpu/drm/bridge/thc63lvd1024.c              |  2 +-
 drivers/gpu/drm/bridge/ti-tfp410.c                 |  2 +-
 drivers/gpu/drm/drm_bridge.c                       | 26 +++++++++++++++++++++-
 drivers/gpu/drm/exynos/exynos_drm_mic.c            |  2 +-
 drivers/gpu/drm/mediatek/mtk_hdmi.c                |  2 +-
 drivers/gpu/drm/msm/dsi/dsi_manager.c              |  1 +
 drivers/gpu/drm/msm/edp/edp_bridge.c               |  1 +
 drivers/gpu/drm/msm/hdmi/hdmi_bridge.c             |  1 +
 drivers/gpu/drm/rcar-du/rcar_lvds.c                |  2 +-
 drivers/gpu/drm/rockchip/rockchip_lvds.c           |  2 +-
 drivers/gpu/drm/sti/sti_dvo.c                      |  2 +-
 drivers/gpu/drm/sti/sti_hda.c                      |  1 +
 drivers/gpu/drm/sti/sti_hdmi.c                     |  1 +
 include/drm/drm_bridge.h                           |  8 +++----
 30 files changed, 57 insertions(+), 36 deletions(-)

-- 
2.11.0

[PATCH v3 01/26] drm/bridge: allow optionally specifying an owner .odev device

[Peter Rosin]

Bridge drivers can now (temporarily, in a transition phase) select if
they want to provide a full owner device or keep just providing an
of_node.

By providing a full owner device, the bridge drivers no longer need
to provide an of_node since that node is available via the owner
device.

When all bridge drivers provide an owner device, that will become
mandatory and the .of_node member will be removed.

There is an interaction with the rockchip lvds driver, since that
driver peeks into somewhat private parts of the bridge struct in
order to find out things about the remote bridge. When there are
now two ways to get to the remote bridge, the rockchip lvds driver
has to adapt. That said, the correct thing to do for the rockchip
lvds driver is to use some other way than DT to find things out
about the remote bridge, but that is orthogonal to this patch.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/gpu/drm/drm_bridge.c             | 3 ++-
 drivers/gpu/drm/rockchip/rockchip_lvds.c | 4 +++-
 include/drm/drm_bridge.h                 | 2 ++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 1638bfe9627c..3872f5379998 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -365,7 +365,8 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 	mutex_lock(&bridge_lock);
 
 	list_for_each_entry(bridge, &bridge_list, list) {
-		if (bridge->of_node == np) {
+		if ((bridge->odev && bridge->odev->of_node == np) ||
+		    bridge->of_node == np) {
 			mutex_unlock(&bridge_lock);
 			return bridge;
 		}
diff --git a/drivers/gpu/drm/rockchip/rockchip_lvds.c b/drivers/gpu/drm/rockchip/rockchip_lvds.c
index 4bd94b167d2c..557e0079c98d 100644
--- a/drivers/gpu/drm/rockchip/rockchip_lvds.c
+++ b/drivers/gpu/drm/rockchip/rockchip_lvds.c
@@ -377,8 +377,10 @@ static int rockchip_lvds_bind(struct device *dev, struct device *master,
 	}
 	if (lvds->panel)
 		remote = lvds->panel->dev->of_node;
-	else
+	else if (lvds->bridge->of_node)
 		remote = lvds->bridge->of_node;
+	else
+		remote = lvds->bridge->odev->of_node;
 	if (of_property_read_string(dev->of_node, "rockchip,output", &name))
 		/* default set it as output rgb */
 		lvds->output = DISPLAY_OUTPUT_RGB;
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 3270fec46979..7c17977c3537 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -254,6 +254,7 @@ struct drm_bridge_timings {
 
 /**
  * struct drm_bridge - central DRM bridge control structure
+ * @odev: device that owns the bridge
  * @dev: DRM device this bridge belongs to
  * @encoder: encoder to which this bridge is connected
  * @next: the next bridge in the encoder chain
@@ -265,6 +266,7 @@ struct drm_bridge_timings {
  * @driver_private: pointer to the bridge driver's internal context
  */
 struct drm_bridge {
+	struct device *odev;
 	struct drm_device *dev;
 	struct drm_encoder *encoder;
 	struct drm_bridge *next;
-- 
2.11.0

[PATCH v3 22/26] drm/rcar-du: lvds: provide an owner .odev device for the bridge

[Peter Rosin]

The .of_node member is going away.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/gpu/drm/rcar-du/rcar_lvds.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
index 3d2d3bbd1342..efda02f55c95 100644
--- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
+++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
@@ -463,9 +463,9 @@ static int rcar_lvds_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return ret;
 
+	lvds->bridge.odev = &pdev->dev;
 	lvds->bridge.driver_private = lvds;
 	lvds->bridge.funcs = &rcar_lvds_bridge_ops;
-	lvds->bridge.of_node = pdev->dev.of_node;
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	lvds->mmio = devm_ioremap_resource(&pdev->dev, mem);
-- 
2.11.0

[PATCH v3 24/26] drm/bridge: remove the .of_node member

[Peter Rosin]

It is unused.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/gpu/drm/drm_bridge.c             | 3 +--
 drivers/gpu/drm/rockchip/rockchip_lvds.c | 2 --
 include/drm/drm_bridge.h                 | 4 ----
 3 files changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 3872f5379998..df084db33494 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -365,8 +365,7 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 	mutex_lock(&bridge_lock);
 
 	list_for_each_entry(bridge, &bridge_list, list) {
-		if ((bridge->odev && bridge->odev->of_node == np) ||
-		    bridge->of_node == np) {
+		if (bridge->odev->of_node == np) {
 			mutex_unlock(&bridge_lock);
 			return bridge;
 		}
diff --git a/drivers/gpu/drm/rockchip/rockchip_lvds.c b/drivers/gpu/drm/rockchip/rockchip_lvds.c
index 557e0079c98d..e77d4c909582 100644
--- a/drivers/gpu/drm/rockchip/rockchip_lvds.c
+++ b/drivers/gpu/drm/rockchip/rockchip_lvds.c
@@ -377,8 +377,6 @@ static int rockchip_lvds_bind(struct device *dev, struct device *master,
 	}
 	if (lvds->panel)
 		remote = lvds->panel->dev->of_node;
-	else if (lvds->bridge->of_node)
-		remote = lvds->bridge->of_node;
 	else
 		remote = lvds->bridge->odev->of_node;
 	if (of_property_read_string(dev->of_node, "rockchip,output", &name))
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 7c17977c3537..b656e505d11e 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -258,7 +258,6 @@ struct drm_bridge_timings {
  * @dev: DRM device this bridge belongs to
  * @encoder: encoder to which this bridge is connected
  * @next: the next bridge in the encoder chain
- * @of_node: device node pointer to the bridge
  * @list: to keep track of all added bridges
  * @timings: the timing specification for the bridge, if any (may
  * be NULL)
@@ -270,9 +269,6 @@ struct drm_bridge {
 	struct drm_device *dev;
 	struct drm_encoder *encoder;
 	struct drm_bridge *next;
-#ifdef CONFIG_OF
-	struct device_node *of_node;
-#endif
 	struct list_head list;
 	const struct drm_bridge_timings *timings;
 
-- 
2.11.0

[PATCH v3 25/26] drm/bridge: require the owner .odev to be filled in on drm_bridge_add/attach

[Peter Rosin]

The .odev owner device will be handy to have around.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/gpu/drm/drm_bridge.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index df084db33494..78d186b6831b 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -70,6 +70,9 @@ static LIST_HEAD(bridge_list);
  */
 void drm_bridge_add(struct drm_bridge *bridge)
 {
+	if (WARN_ON(!bridge->odev))
+		return;
+
 	mutex_lock(&bridge_lock);
 	list_add_tail(&bridge->list, &bridge_list);
 	mutex_unlock(&bridge_lock);
@@ -115,6 +118,9 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 	if (!encoder || !bridge)
 		return -EINVAL;
 
+	if (WARN_ON(!bridge->odev))
+		return -EINVAL;
+
 	if (previous && (!previous->dev || previous->encoder != encoder))
 		return -EINVAL;
 
-- 
2.11.0

[PATCH v3 26/26] drm/bridge: establish a link between the bridge supplier and consumer

[Peter Rosin]

If the bridge supplier is unbound, this will bring the bridge consumer
down along with the bridge. Thus, there will no longer linger any
dangling pointers from the bridge consumer (the drm_device) to some
non-existent bridge supplier.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/gpu/drm/drm_bridge.c | 18 ++++++++++++++++++
 include/drm/drm_bridge.h     |  2 ++
 2 files changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 78d186b6831b..0259f0a3ff27 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -26,6 +26,7 @@
 #include <linux/mutex.h>
 
 #include <drm/drm_bridge.h>
+#include <drm/drm_device.h>
 #include <drm/drm_encoder.h>
 
 #include "drm_crtc_internal.h"
@@ -127,12 +128,25 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 	if (bridge->dev)
 		return -EBUSY;
 
+	if (encoder->dev->dev != bridge->odev) {
+		bridge->link = device_link_add(encoder->dev->dev,
+					       bridge->odev, 0);
+		if (!bridge->link) {
+			dev_err(bridge->odev, "failed to link bridge to %s\n",
+				dev_name(encoder->dev->dev));
+			return -EINVAL;
+		}
+	}
+
 	bridge->dev = encoder->dev;
 	bridge->encoder = encoder;
 
 	if (bridge->funcs->attach) {
 		ret = bridge->funcs->attach(bridge);
 		if (ret < 0) {
+			if (bridge->link)
+				device_link_del(bridge->link);
+			bridge->link = NULL;
 			bridge->dev = NULL;
 			bridge->encoder = NULL;
 			return ret;
@@ -159,6 +173,10 @@ void drm_bridge_detach(struct drm_bridge *bridge)
 	if (bridge->funcs->detach)
 		bridge->funcs->detach(bridge);
 
+	if (bridge->link)
+		device_link_del(bridge->link);
+	bridge->link = NULL;
+
 	bridge->dev = NULL;
 }
 
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index b656e505d11e..bd1265c5a0bc 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -261,6 +261,7 @@ struct drm_bridge_timings {
  * @list: to keep track of all added bridges
  * @timings: the timing specification for the bridge, if any (may
  * be NULL)
+ * @link: device link between the drm consumer and the bridge supplier
  * @funcs: control functions
  * @driver_private: pointer to the bridge driver's internal context
  */
@@ -271,6 +272,7 @@ struct drm_bridge {
 	struct drm_bridge *next;
 	struct list_head list;
 	const struct drm_bridge_timings *timings;
+	struct device_link *link;
 
 	const struct drm_bridge_funcs *funcs;
 	void *driver_private;
-- 
2.11.0

Re: [PATCH v3 01/26] drm/bridge: allow optionally specifying an owner .odev device

[Heiko Stuebner]

Hi Peter,

Am Mittwoch, 16. Mai 2018, 12:14:45 CEST schrieb Peter Rosin:
> Bridge drivers can now (temporarily, in a transition phase) select if
> they want to provide a full owner device or keep just providing an
> of_node.
> 
> By providing a full owner device, the bridge drivers no longer need
> to provide an of_node since that node is available via the owner
> device.
> 
> When all bridge drivers provide an owner device, that will become
> mandatory and the .of_node member will be removed.
> 
> There is an interaction with the rockchip lvds driver, since that
> driver peeks into somewhat private parts of the bridge struct in
> order to find out things about the remote bridge. When there are
> now two ways to get to the remote bridge, the rockchip lvds driver
> has to adapt. That said, the correct thing to do for the rockchip
> lvds driver is to use some other way than DT to find things out
> about the remote bridge, but that is orthogonal to this patch.
> 
> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Peter Rosin <peda@axentia.se>

> diff --git a/drivers/gpu/drm/rockchip/rockchip_lvds.c b/drivers/gpu/drm/rockchip/rockchip_lvds.c
> index 4bd94b167d2c..557e0079c98d 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_lvds.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_lvds.c
> @@ -377,8 +377,10 @@ static int rockchip_lvds_bind(struct device *dev, struct device *master,
>  	}
>  	if (lvds->panel)
>  		remote = lvds->panel->dev->of_node;
> -	else
> +	else if (lvds->bridge->of_node)
>  		remote = lvds->bridge->of_node;
> +	else
> +		remote = lvds->bridge->odev->of_node;
>  	if (of_property_read_string(dev->of_node, "rockchip,output", &name))
>  		/* default set it as output rgb */
>  		lvds->output = DISPLAY_OUTPUT_RGB;

for the Rockchip-part
Acked-by: Heiko Stuebner <heiko@sntech.de>

Re: [PATCH v3 24/26] drm/bridge: remove the .of_node member

[Heiko Stuebner]

Am Mittwoch, 16. Mai 2018, 12:15:08 CEST schrieb Peter Rosin:
> It is unused.
> 
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Peter Rosin <peda@axentia.se>

> diff --git a/drivers/gpu/drm/rockchip/rockchip_lvds.c b/drivers/gpu/drm/rockchip/rockchip_lvds.c
> index 557e0079c98d..e77d4c909582 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_lvds.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_lvds.c
> @@ -377,8 +377,6 @@ static int rockchip_lvds_bind(struct device *dev, struct device *master,
>  	}
>  	if (lvds->panel)
>  		remote = lvds->panel->dev->of_node;
> -	else if (lvds->bridge->of_node)
> -		remote = lvds->bridge->of_node;
>  	else
>  		remote = lvds->bridge->odev->of_node;
>  	if (of_property_read_string(dev->of_node, "rockchip,output", &name))

for the Rockchip-part
Acked-by: Heiko Stuebner <heiko@sntech.de>