[PATCH v1 0/5] mxsfb/nwl/panels: media bus format fixes

[PATCH v1 0/5] mxsfb/nwl/panels: media bus format fixes

[Guido Günther]

commit b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if
present") added bus format probing to mxsfb this exposed several issues in the
display stack as used on the Librem 5:

The nwl bridge and the panels didn't bother to set any media bus formats and in
that case mxsfb would not pick a reasonable default. This series aims to fix
this.

This series includes the patch from
https://lore.kernel.org/dri-devel/YVLYh%2FSgBritG%2FRJ@qwark.sigxcpu.org/
with a `dev_warn` added.

The patches are against 5.15-rc3. I've marked a single patch with a 'fixes'
which is enough to unbreak the display stack in 5.15.


Guido Günther (5):
  drm: mxsfb: Print failed bus format in hex
  drm: mxsfb: Set proper default bus format when using a bridge
  drm/bridge: nwl-dsi: Add atomic_get_input_bus_fmts
  drm/panel: mantix: Add media bus format
  drm/panel: st7703: Add media bus format

 drivers/gpu/drm/bridge/nwl-dsi.c              | 35 +++++++++++++++++++
 drivers/gpu/drm/mxsfb/mxsfb_kms.c             |  7 +++-
 .../gpu/drm/panel/panel-mantix-mlaf057we51.c  |  9 +++++
 drivers/gpu/drm/panel/panel-sitronix-st7703.c |  8 +++++
 4 files changed, 58 insertions(+), 1 deletion(-)

-- 
2.33.0

[PATCH v1 0/5] mxsfb/nwl/panels: media bus format fixes

[Guido Günther]

commit b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if
present") added bus format probing to mxsfb this exposed several issues in the
display stack as used on the Librem 5:

The nwl bridge and the panels didn't bother to set any media bus formats and in
that case mxsfb would not pick a reasonable default. This series aims to fix
this.

This series includes the patch from
https://lore.kernel.org/dri-devel/YVLYh%2FSgBritG%2FRJ@qwark.sigxcpu.org/
with a `dev_warn` added.

The patches are against 5.15-rc3. I've marked a single patch with a 'fixes'
which is enough to unbreak the display stack in 5.15.


Guido Günther (5):
  drm: mxsfb: Print failed bus format in hex
  drm: mxsfb: Set proper default bus format when using a bridge
  drm/bridge: nwl-dsi: Add atomic_get_input_bus_fmts
  drm/panel: mantix: Add media bus format
  drm/panel: st7703: Add media bus format

 drivers/gpu/drm/bridge/nwl-dsi.c              | 35 +++++++++++++++++++
 drivers/gpu/drm/mxsfb/mxsfb_kms.c             |  7 +++-
 .../gpu/drm/panel/panel-mantix-mlaf057we51.c  |  9 +++++
 drivers/gpu/drm/panel/panel-sitronix-st7703.c |  8 +++++
 4 files changed, 58 insertions(+), 1 deletion(-)

-- 
2.33.0


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[PATCH v1 1/5] drm: mxsfb: Print failed bus format in hex

[Guido Günther]

media-bus-formats.h has them in hexadecimal as well so matching with
that file saves one conversion when debugging.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index af6c620adf6e..d6abd2077114 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -89,7 +89,7 @@ static void mxsfb_set_formats(struct mxsfb_drm_private *mxsfb,
 		ctrl |= CTRL_BUS_WIDTH_24;
 		break;
 	default:
-		dev_err(drm->dev, "Unknown media bus format %d\n", bus_format);
+		dev_err(drm->dev, "Unknown media bus format 0x%x\n", bus_format);
 		break;
 	}
 
-- 
2.33.0

[PATCH v1 1/5] drm: mxsfb: Print failed bus format in hex

[Guido Günther]

media-bus-formats.h has them in hexadecimal as well so matching with
that file saves one conversion when debugging.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index af6c620adf6e..d6abd2077114 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -89,7 +89,7 @@ static void mxsfb_set_formats(struct mxsfb_drm_private *mxsfb,
 		ctrl |= CTRL_BUS_WIDTH_24;
 		break;
 	default:
-		dev_err(drm->dev, "Unknown media bus format %d\n", bus_format);
+		dev_err(drm->dev, "Unknown media bus format 0x%x\n", bus_format);
 		break;
 	}
 
-- 
2.33.0


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[PATCH v1 2/5] drm: mxsfb: Set proper default bus format when using a bridge

[Guido Günther]

If a bridge doesn't do any bus format handling MEDIA_BUS_FMT_FIXED is
returned. Fallback to a reasonable default (MEDIA_BUS_FMT_RGB888_1X24) in
that case.

This unbreaks e.g. using mxsfb with the nwl bridge and mipi panels.

Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")

Reported-by: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index d6abd2077114..f4be16f5c20b 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -369,6 +369,11 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc,
 			drm_atomic_get_new_bridge_state(state,
 							mxsfb->bridge);
 		bus_format = bridge_state->input_bus_cfg.format;
+		if (bus_format == MEDIA_BUS_FMT_FIXED) {
+			dev_warn_once(drm->dev,
+				      "Bridge does not provide bus format. Please fix.");
+			bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+		}
 	}
 
 	/* If there is no bridge, use bus format from connector */
-- 
2.33.0

[PATCH v1 2/5] drm: mxsfb: Set proper default bus format when using a bridge

[Guido Günther]

If a bridge doesn't do any bus format handling MEDIA_BUS_FMT_FIXED is
returned. Fallback to a reasonable default (MEDIA_BUS_FMT_RGB888_1X24) in
that case.

This unbreaks e.g. using mxsfb with the nwl bridge and mipi panels.

Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")

Reported-by: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index d6abd2077114..f4be16f5c20b 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -369,6 +369,11 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc,
 			drm_atomic_get_new_bridge_state(state,
 							mxsfb->bridge);
 		bus_format = bridge_state->input_bus_cfg.format;
+		if (bus_format == MEDIA_BUS_FMT_FIXED) {
+			dev_warn_once(drm->dev,
+				      "Bridge does not provide bus format. Please fix.");
+			bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+		}
 	}
 
 	/* If there is no bridge, use bus format from connector */
-- 
2.33.0


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[PATCH v1 3/5] drm/bridge: nwl-dsi: Add atomic_get_input_bus_fmts

[Guido Günther]

Components further up in the chain might ask us for supported formats.

Without this MEDIA_BUS_FMT_FIXED is assumed which then breaks display
output with mxsfb since it can't determine a proper bus format.

We handle the bus formats that correspond to the DSI formats the bridge
can potentially output (see chapter 13.6 of the i.MX 8MQ reference
manual) - which matches what xsfb can input.

Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/bridge/nwl-dsi.c | 35 ++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
index a251cc1f088f..27c80d36846b 100644
--- a/drivers/gpu/drm/bridge/nwl-dsi.c
+++ b/drivers/gpu/drm/bridge/nwl-dsi.c
@@ -1234,6 +1234,40 @@ static void nwl_dsi_bridge_detach(struct drm_bridge *bridge)
 	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
 }
 
+static u32 *nwl_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
+						 struct drm_bridge_state *bridge_state,
+						 struct drm_crtc_state *crtc_state,
+						 struct drm_connector_state *conn_state,
+						 u32 output_fmt,
+						 unsigned int *num_input_fmts)
+{
+	u32 *input_fmts, input_fmt;
+
+	*num_input_fmts = 0;
+
+	switch (output_fmt) {
+	/* If MEDIA_BUS_FMT_FIXED is tested, return default bus format */
+	case MEDIA_BUS_FMT_FIXED:
+		input_fmt = MEDIA_BUS_FMT_RGB888_1X24;
+		break;
+	case MEDIA_BUS_FMT_RGB888_1X24:
+	case MEDIA_BUS_FMT_RGB666_1X18:
+	case MEDIA_BUS_FMT_RGB565_1X16:
+		input_fmt = output_fmt;
+		break;
+	default:
+		return NULL;
+	}
+
+	input_fmts = kcalloc(1, sizeof(*input_fmts), GFP_KERNEL);
+	if (!input_fmts)
+		return NULL;
+	input_fmts[0] = input_fmt;
+	*num_input_fmts = 1;
+
+	return input_fmts;
+}
+
 static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
 	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
@@ -1241,6 +1275,7 @@ static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
 	.atomic_check		= nwl_dsi_bridge_atomic_check,
 	.atomic_enable		= nwl_dsi_bridge_atomic_enable,
 	.atomic_disable		= nwl_dsi_bridge_atomic_disable,
+	.atomic_get_input_bus_fmts = nwl_bridge_atomic_get_input_bus_fmts,
 	.mode_set		= nwl_dsi_bridge_mode_set,
 	.mode_valid		= nwl_dsi_bridge_mode_valid,
 	.attach			= nwl_dsi_bridge_attach,
-- 
2.33.0

[PATCH v1 3/5] drm/bridge: nwl-dsi: Add atomic_get_input_bus_fmts

[Guido Günther]

Components further up in the chain might ask us for supported formats.

Without this MEDIA_BUS_FMT_FIXED is assumed which then breaks display
output with mxsfb since it can't determine a proper bus format.

We handle the bus formats that correspond to the DSI formats the bridge
can potentially output (see chapter 13.6 of the i.MX 8MQ reference
manual) - which matches what xsfb can input.

Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/bridge/nwl-dsi.c | 35 ++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
index a251cc1f088f..27c80d36846b 100644
--- a/drivers/gpu/drm/bridge/nwl-dsi.c
+++ b/drivers/gpu/drm/bridge/nwl-dsi.c
@@ -1234,6 +1234,40 @@ static void nwl_dsi_bridge_detach(struct drm_bridge *bridge)
 	drm_of_panel_bridge_remove(dsi->dev->of_node, 1, 0);
 }
 
+static u32 *nwl_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
+						 struct drm_bridge_state *bridge_state,
+						 struct drm_crtc_state *crtc_state,
+						 struct drm_connector_state *conn_state,
+						 u32 output_fmt,
+						 unsigned int *num_input_fmts)
+{
+	u32 *input_fmts, input_fmt;
+
+	*num_input_fmts = 0;
+
+	switch (output_fmt) {
+	/* If MEDIA_BUS_FMT_FIXED is tested, return default bus format */
+	case MEDIA_BUS_FMT_FIXED:
+		input_fmt = MEDIA_BUS_FMT_RGB888_1X24;
+		break;
+	case MEDIA_BUS_FMT_RGB888_1X24:
+	case MEDIA_BUS_FMT_RGB666_1X18:
+	case MEDIA_BUS_FMT_RGB565_1X16:
+		input_fmt = output_fmt;
+		break;
+	default:
+		return NULL;
+	}
+
+	input_fmts = kcalloc(1, sizeof(*input_fmts), GFP_KERNEL);
+	if (!input_fmts)
+		return NULL;
+	input_fmts[0] = input_fmt;
+	*num_input_fmts = 1;
+
+	return input_fmts;
+}
+
 static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
 	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
@@ -1241,6 +1275,7 @@ static const struct drm_bridge_funcs nwl_dsi_bridge_funcs = {
 	.atomic_check		= nwl_dsi_bridge_atomic_check,
 	.atomic_enable		= nwl_dsi_bridge_atomic_enable,
 	.atomic_disable		= nwl_dsi_bridge_atomic_disable,
+	.atomic_get_input_bus_fmts = nwl_bridge_atomic_get_input_bus_fmts,
 	.mode_set		= nwl_dsi_bridge_mode_set,
 	.mode_valid		= nwl_dsi_bridge_mode_valid,
 	.attach			= nwl_dsi_bridge_attach,
-- 
2.33.0


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[PATCH v1 4/5] drm/panel: mantix: Add media bus format

[Guido Günther]

This allows the DSI bridge to detect the correct bus format.
We currently only support MEDIA_BUS_FMT_RGB888_1X24.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c b/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
index f0e9bce23c41..d6bcf1045255 100644
--- a/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
+++ b/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
@@ -8,6 +8,7 @@
 #include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
+#include <linux/media-bus-format.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/regulator/consumer.h>
@@ -232,6 +233,10 @@ static const struct drm_display_mode default_mode_ys = {
 	.height_mm   = 130,
 };
 
+static const u32 mantix_bus_formats[] = {
+	MEDIA_BUS_FMT_RGB888_1X24,
+};
+
 static int mantix_get_modes(struct drm_panel *panel,
 			    struct drm_connector *connector)
 {
@@ -253,6 +258,10 @@ static int mantix_get_modes(struct drm_panel *panel,
 	connector->display_info.height_mm = mode->height_mm;
 	drm_mode_probed_add(connector, mode);
 
+	drm_display_info_set_bus_formats(&connector->display_info,
+					 mantix_bus_formats,
+					 ARRAY_SIZE(mantix_bus_formats));
+
 	return 1;
 }
 
-- 
2.33.0

[PATCH v1 4/5] drm/panel: mantix: Add media bus format

[Guido Günther]

This allows the DSI bridge to detect the correct bus format.
We currently only support MEDIA_BUS_FMT_RGB888_1X24.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c b/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
index f0e9bce23c41..d6bcf1045255 100644
--- a/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
+++ b/drivers/gpu/drm/panel/panel-mantix-mlaf057we51.c
@@ -8,6 +8,7 @@
 #include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
+#include <linux/media-bus-format.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/regulator/consumer.h>
@@ -232,6 +233,10 @@ static const struct drm_display_mode default_mode_ys = {
 	.height_mm   = 130,
 };
 
+static const u32 mantix_bus_formats[] = {
+	MEDIA_BUS_FMT_RGB888_1X24,
+};
+
 static int mantix_get_modes(struct drm_panel *panel,
 			    struct drm_connector *connector)
 {
@@ -253,6 +258,10 @@ static int mantix_get_modes(struct drm_panel *panel,
 	connector->display_info.height_mm = mode->height_mm;
 	drm_mode_probed_add(connector, mode);
 
+	drm_display_info_set_bus_formats(&connector->display_info,
+					 mantix_bus_formats,
+					 ARRAY_SIZE(mantix_bus_formats));
+
 	return 1;
 }
 
-- 
2.33.0


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[PATCH v1 5/5] drm/panel: st7703: Add media bus format

[Guido Günther]

This allows the DSI bridge to detect the correct bus format.
We currently only support MEDIA_BUS_FMT_RGB888_1X24.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/panel/panel-sitronix-st7703.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7703.c b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
index a2c303e5732c..73f69c929a75 100644
--- a/drivers/gpu/drm/panel/panel-sitronix-st7703.c
+++ b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
@@ -453,6 +453,10 @@ static int st7703_prepare(struct drm_panel *panel)
 	return ret;
 }
 
+static const u32 mantix_bus_formats[] = {
+	MEDIA_BUS_FMT_RGB888_1X24,
+};
+
 static int st7703_get_modes(struct drm_panel *panel,
 			    struct drm_connector *connector)
 {
@@ -474,6 +478,10 @@ static int st7703_get_modes(struct drm_panel *panel,
 	connector->display_info.height_mm = mode->height_mm;
 	drm_mode_probed_add(connector, mode);
 
+	drm_display_info_set_bus_formats(&connector->display_info,
+					 mantix_bus_formats,
+					 ARRAY_SIZE(mantix_bus_formats));
+
 	return 1;
 }
 
-- 
2.33.0

[PATCH v1 5/5] drm/panel: st7703: Add media bus format

[Guido Günther]

This allows the DSI bridge to detect the correct bus format.
We currently only support MEDIA_BUS_FMT_RGB888_1X24.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 drivers/gpu/drm/panel/panel-sitronix-st7703.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7703.c b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
index a2c303e5732c..73f69c929a75 100644
--- a/drivers/gpu/drm/panel/panel-sitronix-st7703.c
+++ b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
@@ -453,6 +453,10 @@ static int st7703_prepare(struct drm_panel *panel)
 	return ret;
 }
 
+static const u32 mantix_bus_formats[] = {
+	MEDIA_BUS_FMT_RGB888_1X24,
+};
+
 static int st7703_get_modes(struct drm_panel *panel,
 			    struct drm_connector *connector)
 {
@@ -474,6 +478,10 @@ static int st7703_get_modes(struct drm_panel *panel,
 	connector->display_info.height_mm = mode->height_mm;
 	drm_mode_probed_add(connector, mode);
 
+	drm_display_info_set_bus_formats(&connector->display_info,
+					 mantix_bus_formats,
+					 ARRAY_SIZE(mantix_bus_formats));
+
 	return 1;
 }
 
-- 
2.33.0


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Re: [PATCH v1 2/5] drm: mxsfb: Set proper default bus format when using a bridge

[Marek Vasut]

On 9/28/21 2:16 PM, Guido Günther wrote:
> If a bridge doesn't do any bus format handling MEDIA_BUS_FMT_FIXED is
> returned. Fallback to a reasonable default (MEDIA_BUS_FMT_RGB888_1X24) in
> that case.
> 
> This unbreaks e.g. using mxsfb with the nwl bridge and mipi panels.
> 
> Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")
> 
> Reported-by: Martin Kepplinger <martink@posteo.de>
> Signed-off-by: Guido Günther <agx@sigxcpu.org>
> ---
>   drivers/gpu/drm/mxsfb/mxsfb_kms.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> index d6abd2077114..f4be16f5c20b 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> @@ -369,6 +369,11 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc,
>   			drm_atomic_get_new_bridge_state(state,
>   							mxsfb->bridge);
>   		bus_format = bridge_state->input_bus_cfg.format;
> +		if (bus_format == MEDIA_BUS_FMT_FIXED) {
> +			dev_warn_once(drm->dev,
> +				      "Bridge does not provide bus format. Please fix.");

Fix what ? Oh ... the bridge driver ?

Maybe such a hint should be in the warning message. And it might be 
useful to explain how to fix that bridge driver, or at least provide 
some reference to an example (like this nwl patch series).

> +			bus_format = MEDIA_BUS_FMT_RGB888_1X24;

The warning should also mention that the driver is falling back to this 
mode.

Re: [PATCH v1 2/5] drm: mxsfb: Set proper default bus format when using a bridge

[Marek Vasut]

On 9/28/21 2:16 PM, Guido Günther wrote:
> If a bridge doesn't do any bus format handling MEDIA_BUS_FMT_FIXED is
> returned. Fallback to a reasonable default (MEDIA_BUS_FMT_RGB888_1X24) in
> that case.
> 
> This unbreaks e.g. using mxsfb with the nwl bridge and mipi panels.
> 
> Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")
> 
> Reported-by: Martin Kepplinger <martink@posteo.de>
> Signed-off-by: Guido Günther <agx@sigxcpu.org>
> ---
>   drivers/gpu/drm/mxsfb/mxsfb_kms.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> index d6abd2077114..f4be16f5c20b 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> @@ -369,6 +369,11 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc,
>   			drm_atomic_get_new_bridge_state(state,
>   							mxsfb->bridge);
>   		bus_format = bridge_state->input_bus_cfg.format;
> +		if (bus_format == MEDIA_BUS_FMT_FIXED) {
> +			dev_warn_once(drm->dev,
> +				      "Bridge does not provide bus format. Please fix.");

Fix what ? Oh ... the bridge driver ?

Maybe such a hint should be in the warning message. And it might be 
useful to explain how to fix that bridge driver, or at least provide 
some reference to an example (like this nwl patch series).

> +			bus_format = MEDIA_BUS_FMT_RGB888_1X24;

The warning should also mention that the driver is falling back to this 
mode.

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Re: [PATCH v1 1/5] drm: mxsfb: Print failed bus format in hex

[Robert Foss]

On Tue, 28 Sept 2021 at 14:16, Guido Günther <agx@sigxcpu.org> wrote:
>
> media-bus-formats.h has them in hexadecimal as well so matching with
> that file saves one conversion when debugging.
>
> Signed-off-by: Guido Günther <agx@sigxcpu.org>
> ---
>  drivers/gpu/drm/mxsfb/mxsfb_kms.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> index af6c620adf6e..d6abd2077114 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> @@ -89,7 +89,7 @@ static void mxsfb_set_formats(struct mxsfb_drm_private *mxsfb,
>                 ctrl |= CTRL_BUS_WIDTH_24;
>                 break;
>         default:
> -               dev_err(drm->dev, "Unknown media bus format %d\n", bus_format);
> +               dev_err(drm->dev, "Unknown media bus format 0x%x\n", bus_format);
>                 break;
>         }

Reviewed-by: Robert Foss <robert.foss@linaro.org>

Re: [PATCH v1 1/5] drm: mxsfb: Print failed bus format in hex

[Robert Foss]

On Tue, 28 Sept 2021 at 14:16, Guido Günther <agx@sigxcpu.org> wrote:
>
> media-bus-formats.h has them in hexadecimal as well so matching with
> that file saves one conversion when debugging.
>
> Signed-off-by: Guido Günther <agx@sigxcpu.org>
> ---
>  drivers/gpu/drm/mxsfb/mxsfb_kms.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> index af6c620adf6e..d6abd2077114 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
> @@ -89,7 +89,7 @@ static void mxsfb_set_formats(struct mxsfb_drm_private *mxsfb,
>                 ctrl |= CTRL_BUS_WIDTH_24;
>                 break;
>         default:
> -               dev_err(drm->dev, "Unknown media bus format %d\n", bus_format);
> +               dev_err(drm->dev, "Unknown media bus format 0x%x\n", bus_format);
>                 break;
>         }

Reviewed-by: Robert Foss <robert.foss@linaro.org>

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