diff mbox series

[v3,1/2] drm/bridge-connector: Prioritize supported_formats over ycbcr_420_allowed

Message ID 20241217-bridge-conn-fmt-prio-v3-1-3ecb3c8fc06f@collabora.com (mailing list archive)
State New
Headers show
Series Fix ycbcr_420_allowed inconsistency for HDMI bridges | expand

Commit Message

Cristian Ciocaltea Dec. 16, 2024, 10:54 p.m. UTC
Bridges having the DRM_BRIDGE_OP_HDMI flag set in drm_bridge->ops are
supposed to rely on drm_bridge->supported_formats bitmask to advertise
the supported colorspaces, including HDMI_COLORSPACE_YUV420.  Therefore,
the newly introduced drm_bridge->ycbcr_420_allowed flag becomes
redundant in this particular context.

Moreover, when drm_bridge_connector gets initialised, only
drm_bridge->ycbcr_420_allowed is considered in the process of adjusting
the equivalent property of the base drm_connector, which effectively
discards the formats advertised by the HDMI bridge.

Handle the inconsistency by overwriting drm_bridge->ycbcr_420_allowed
for HDMI bridges according to drm_bridge->supported_formats, before
adding them to the global bridge list.

Additionally, ensure the YUV420 related bit is removed from the bitmask
passed to drmm_connector_hdmi_init() when the final ycbcr_420_allowed
flag for the connector ends up not being set (i.e. the case of having at
least one non-HDMI bridge in the pipeline that didn't enable it).

Fixes: 3ced1c687512 ("drm/display: bridge_connector: handle ycbcr_420_allowed")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/gpu/drm/display/drm_bridge_connector.c | 8 ++++++--
 drivers/gpu/drm/drm_bridge.c                   | 4 ++++
 2 files changed, 10 insertions(+), 2 deletions(-)

Comments

Dmitry Baryshkov Dec. 16, 2024, 11:27 p.m. UTC | #1
On Tue, Dec 17, 2024 at 12:54:07AM +0200, Cristian Ciocaltea wrote:
> Bridges having the DRM_BRIDGE_OP_HDMI flag set in drm_bridge->ops are
> supposed to rely on drm_bridge->supported_formats bitmask to advertise
> the supported colorspaces, including HDMI_COLORSPACE_YUV420.  Therefore,
> the newly introduced drm_bridge->ycbcr_420_allowed flag becomes
> redundant in this particular context.
> 
> Moreover, when drm_bridge_connector gets initialised, only
> drm_bridge->ycbcr_420_allowed is considered in the process of adjusting
> the equivalent property of the base drm_connector, which effectively
> discards the formats advertised by the HDMI bridge.
> 
> Handle the inconsistency by overwriting drm_bridge->ycbcr_420_allowed
> for HDMI bridges according to drm_bridge->supported_formats, before
> adding them to the global bridge list.
> 
> Additionally, ensure the YUV420 related bit is removed from the bitmask
> passed to drmm_connector_hdmi_init() when the final ycbcr_420_allowed
> flag for the connector ends up not being set (i.e. the case of having at
> least one non-HDMI bridge in the pipeline that didn't enable it).
> 
> Fixes: 3ced1c687512 ("drm/display: bridge_connector: handle ycbcr_420_allowed")
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> ---
>  drivers/gpu/drm/display/drm_bridge_connector.c | 8 ++++++--
>  drivers/gpu/drm/drm_bridge.c                   | 4 ++++
>  2 files changed, 10 insertions(+), 2 deletions(-)

I think the second patch in the series is enough, it ensures that
connector's state is consistent, no matter if the drm_bridge_connector
is being used or a normal drm_connector.

Nevertheless, I'd leave the final decision to DRM maintainers.
Cristian Ciocaltea Dec. 17, 2024, 12:38 a.m. UTC | #2
On 12/17/24 1:27 AM, Dmitry Baryshkov wrote:
> On Tue, Dec 17, 2024 at 12:54:07AM +0200, Cristian Ciocaltea wrote:
>> Bridges having the DRM_BRIDGE_OP_HDMI flag set in drm_bridge->ops are
>> supposed to rely on drm_bridge->supported_formats bitmask to advertise
>> the supported colorspaces, including HDMI_COLORSPACE_YUV420.  Therefore,
>> the newly introduced drm_bridge->ycbcr_420_allowed flag becomes
>> redundant in this particular context.
>>
>> Moreover, when drm_bridge_connector gets initialised, only
>> drm_bridge->ycbcr_420_allowed is considered in the process of adjusting
>> the equivalent property of the base drm_connector, which effectively
>> discards the formats advertised by the HDMI bridge.
>>
>> Handle the inconsistency by overwriting drm_bridge->ycbcr_420_allowed
>> for HDMI bridges according to drm_bridge->supported_formats, before
>> adding them to the global bridge list.
>>
>> Additionally, ensure the YUV420 related bit is removed from the bitmask
>> passed to drmm_connector_hdmi_init() when the final ycbcr_420_allowed
>> flag for the connector ends up not being set (i.e. the case of having at
>> least one non-HDMI bridge in the pipeline that didn't enable it).
>>
>> Fixes: 3ced1c687512 ("drm/display: bridge_connector: handle ycbcr_420_allowed")
>> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
>> ---
>>  drivers/gpu/drm/display/drm_bridge_connector.c | 8 ++++++--
>>  drivers/gpu/drm/drm_bridge.c                   | 4 ++++
>>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> I think the second patch in the series is enough, it ensures that
> connector's state is consistent, no matter if the drm_bridge_connector
> is being used or a normal drm_connector.
> 
> Nevertheless, I'd leave the final decision to DRM maintainers.

This patch has 2 parts, maybe I should have put them into separate patches
as they kind of relate to distinct problems.

The 1st part makes sure that drm_bridge->ycbcr_420_allowed is automatically
set when HDMI_COLORSPACE_YUV420 is provided in drm_bridge->supported_formats, 
to avoid the need of requiring redundant information on HDMI bridges 
initialization.  This implicitly ensures the consistency needed to further 
allow relying on ->ycbcr_420_allowed internally.

While the 1st part could be dropped (assuming redundancy & consistency is
not really something we want/need to handle), the 2nd part I think is
mandatory, i.e. we must adjust supported_formats before calling
drmm_connector_hdmi_init() to ensure the presence of HDMI_COLORSPACE_YUV420
reflects the status of the computed connector->ycbcr_420_allowed, which
might end up being different than what the HDMI bridge advertised, i.e. the
case of having an HDMI bridge in the pipeline advertising YUV420 via 
supported_formats and a non-HDMI one that didn't enable ycbcr_420_allowed.

Thanks,
Cristian
Dmitry Baryshkov Dec. 20, 2024, 1:05 a.m. UTC | #3
On Tue, Dec 17, 2024 at 02:38:55AM +0200, Cristian Ciocaltea wrote:
> On 12/17/24 1:27 AM, Dmitry Baryshkov wrote:
> > On Tue, Dec 17, 2024 at 12:54:07AM +0200, Cristian Ciocaltea wrote:
> >> Bridges having the DRM_BRIDGE_OP_HDMI flag set in drm_bridge->ops are
> >> supposed to rely on drm_bridge->supported_formats bitmask to advertise
> >> the supported colorspaces, including HDMI_COLORSPACE_YUV420.  Therefore,
> >> the newly introduced drm_bridge->ycbcr_420_allowed flag becomes
> >> redundant in this particular context.
> >>
> >> Moreover, when drm_bridge_connector gets initialised, only
> >> drm_bridge->ycbcr_420_allowed is considered in the process of adjusting
> >> the equivalent property of the base drm_connector, which effectively
> >> discards the formats advertised by the HDMI bridge.
> >>
> >> Handle the inconsistency by overwriting drm_bridge->ycbcr_420_allowed
> >> for HDMI bridges according to drm_bridge->supported_formats, before
> >> adding them to the global bridge list.
> >>
> >> Additionally, ensure the YUV420 related bit is removed from the bitmask
> >> passed to drmm_connector_hdmi_init() when the final ycbcr_420_allowed
> >> flag for the connector ends up not being set (i.e. the case of having at
> >> least one non-HDMI bridge in the pipeline that didn't enable it).
> >>
> >> Fixes: 3ced1c687512 ("drm/display: bridge_connector: handle ycbcr_420_allowed")
> >> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> >> ---
> >>  drivers/gpu/drm/display/drm_bridge_connector.c | 8 ++++++--
> >>  drivers/gpu/drm/drm_bridge.c                   | 4 ++++
> >>  2 files changed, 10 insertions(+), 2 deletions(-)
> > 
> > I think the second patch in the series is enough, it ensures that
> > connector's state is consistent, no matter if the drm_bridge_connector
> > is being used or a normal drm_connector.
> > 
> > Nevertheless, I'd leave the final decision to DRM maintainers.
> 
> This patch has 2 parts, maybe I should have put them into separate patches
> as they kind of relate to distinct problems.
> 
> The 1st part makes sure that drm_bridge->ycbcr_420_allowed is automatically
> set when HDMI_COLORSPACE_YUV420 is provided in drm_bridge->supported_formats, 
> to avoid the need of requiring redundant information on HDMI bridges 
> initialization.  This implicitly ensures the consistency needed to further 
> allow relying on ->ycbcr_420_allowed internally.
> 
> While the 1st part could be dropped (assuming redundancy & consistency is
> not really something we want/need to handle), the 2nd part I think is
> mandatory, i.e. we must adjust supported_formats before calling
> drmm_connector_hdmi_init() to ensure the presence of HDMI_COLORSPACE_YUV420
> reflects the status of the computed connector->ycbcr_420_allowed, which
> might end up being different than what the HDMI bridge advertised, i.e. the
> case of having an HDMI bridge in the pipeline advertising YUV420 via 
> supported_formats and a non-HDMI one that didn't enable ycbcr_420_allowed.

Please split it into two patches. I don't have a strong opinion upon the
first one (I'd change it to dev_warn() maybe), while the second one
(removing HDMI_COLORSPACE_YUV420 if connector->ycbcr_420_allowed is
false) is definitely a correct change.

> 
> Thanks,
> Cristian
diff mbox series

Patch

diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
index 320c297008aaa8b6ef5b1f4c71928849b202e8ac..3a5a4f92c979accaa2a8f79ca0f15396dd579429 100644
--- a/drivers/gpu/drm/display/drm_bridge_connector.c
+++ b/drivers/gpu/drm/display/drm_bridge_connector.c
@@ -459,7 +459,10 @@  struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 	if (connector_type == DRM_MODE_CONNECTOR_Unknown)
 		return ERR_PTR(-EINVAL);
 
-	if (bridge_connector->bridge_hdmi)
+	if (bridge_connector->bridge_hdmi) {
+		if (!connector->ycbcr_420_allowed)
+			supported_formats &= ~BIT(HDMI_COLORSPACE_YUV420);
+
 		ret = drmm_connector_hdmi_init(drm, connector,
 					       bridge_connector->bridge_hdmi->vendor,
 					       bridge_connector->bridge_hdmi->product,
@@ -468,10 +471,11 @@  struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 					       connector_type, ddc,
 					       supported_formats,
 					       max_bpc);
-	else
+	} else {
 		ret = drmm_connector_init(drm, connector,
 					  &drm_bridge_connector_funcs,
 					  connector_type, ddc);
+	}
 	if (ret)
 		return ERR_PTR(ret);
 
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index c6af46dd02bfa9e15b59e4c460debdd7fd84be44..241a384ebce39b4a3db58c208af27960904fc662 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -207,6 +207,10 @@  void drm_bridge_add(struct drm_bridge *bridge)
 {
 	mutex_init(&bridge->hpd_mutex);
 
+	if (bridge->ops & DRM_BRIDGE_OP_HDMI)
+		bridge->ycbcr_420_allowed = !!(bridge->supported_formats &
+					       BIT(HDMI_COLORSPACE_YUV420));
+
 	mutex_lock(&bridge_lock);
 	list_add_tail(&bridge->list, &bridge_list);
 	mutex_unlock(&bridge_lock);