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[PATCH v7 01/18] drm/display: bridge_connector: Ensure last bridge determines EDID/modes detection capabilities

Damon Ding posted 18 patches 1 month, 3 weeks ago
Only 6 patches received!
There is a newer version of this series
[PATCH v7 01/18] drm/display: bridge_connector: Ensure last bridge determines EDID/modes detection capabilities
Posted by Damon Ding 1 month, 3 weeks ago 
When multiple bridges are present, EDID detection capability
(DRM_BRIDGE_OP_EDID) takes precedence over modes detection
(DRM_BRIDGE_OP_MODES). To ensure the above two capabilities are
determined by the last bridge in the chain, we handle three cases:

Case 1: The later bridge declares only DRM_BRIDGE_OP_MODES
 - If the previous bridge declares DRM_BRIDGE_OP_EDID, set
   &drm_bridge_connector.bridge_edid to NULL and set
   &drm_bridge_connector.bridge_modes to the later bridge.
 - Ensure modes detection capability of the later bridge will not
   be ignored.

Case 2: The later bridge declares only DRM_BRIDGE_OP_EDID
 - If the previous bridge declares DRM_BRIDGE_OP_MODES, set
   &drm_bridge_connector.bridge_modes to NULL and set
   &drm_bridge_connector.bridge_edid to the later bridge.
 - Although EDID detection capability has higher priority, this
   operation is for balance and makes sense.

Case 3: the later bridge declares both of them
 - Assign later bridge as &drm_bridge_connector.bridge_edid and
   and &drm_bridge_connector.bridge_modes to this bridge.
 - Just leave transfer of these two capabilities as before.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

---

Changes in v7:
- As Luca suggested, simplify the code and related comment.
---
 drivers/gpu/drm/display/drm_bridge_connector.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
index baacd21e7341..7c2936d59517 100644
--- a/drivers/gpu/drm/display/drm_bridge_connector.c
+++ b/drivers/gpu/drm/display/drm_bridge_connector.c
@@ -673,14 +673,22 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 		if (!bridge->ycbcr_420_allowed)
 			connector->ycbcr_420_allowed = false;
 
-		if (bridge->ops & DRM_BRIDGE_OP_EDID)
-			bridge_connector->bridge_edid = bridge;
+		/*
+		 * Ensure the last bridge declares OP_EDID or OP_MODES or both.
+		 */
+		if (bridge->ops & DRM_BRIDGE_OP_EDID || bridge->ops & DRM_BRIDGE_OP_MODES) {
+			bridge_connector->bridge_edid = NULL;
+			bridge_connector->bridge_modes = NULL;
+			if (bridge->ops & DRM_BRIDGE_OP_EDID)
+				bridge_connector->bridge_edid = bridge;
+			if (bridge->ops & DRM_BRIDGE_OP_MODES)
+				bridge_connector->bridge_modes = bridge;
+		}
 		if (bridge->ops & DRM_BRIDGE_OP_HPD)
 			bridge_connector->bridge_hpd = bridge;
 		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
 			bridge_connector->bridge_detect = bridge;
-		if (bridge->ops & DRM_BRIDGE_OP_MODES)
-			bridge_connector->bridge_modes = bridge;
+
 		if (bridge->ops & DRM_BRIDGE_OP_HDMI) {
 			if (bridge_connector->bridge_hdmi)
 				return ERR_PTR(-EBUSY);
-- 
2.34.1
Re: [PATCH v7 01/18] drm/display: bridge_connector: Ensure last bridge determines EDID/modes detection capabilities
Posted by Luca Ceresoli 1 month, 3 weeks ago 
Hello Damon,

On Tue Oct 21, 2025 at 4:31 AM CEST, Damon Ding wrote:
> When multiple bridges are present, EDID detection capability
> (DRM_BRIDGE_OP_EDID) takes precedence over modes detection
> (DRM_BRIDGE_OP_MODES). To ensure the above two capabilities are
> determined by the last bridge in the chain, we handle three cases:
>
> Case 1: The later bridge declares only DRM_BRIDGE_OP_MODES
>  - If the previous bridge declares DRM_BRIDGE_OP_EDID, set
>    &drm_bridge_connector.bridge_edid to NULL and set
>    &drm_bridge_connector.bridge_modes to the later bridge.
>  - Ensure modes detection capability of the later bridge will not
>    be ignored.
>
> Case 2: The later bridge declares only DRM_BRIDGE_OP_EDID
>  - If the previous bridge declares DRM_BRIDGE_OP_MODES, set
>    &drm_bridge_connector.bridge_modes to NULL and set
>    &drm_bridge_connector.bridge_edid to the later bridge.
>  - Although EDID detection capability has higher priority, this
>    operation is for balance and makes sense.
>
> Case 3: the later bridge declares both of them
>  - Assign later bridge as &drm_bridge_connector.bridge_edid and
>    and &drm_bridge_connector.bridge_modes to this bridge.
>  - Just leave transfer of these two capabilities as before.
>
> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
>
> ---
>
> Changes in v7:
> - As Luca suggested, simplify the code and related comment.
> ---
>  drivers/gpu/drm/display/drm_bridge_connector.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
> index baacd21e7341..7c2936d59517 100644
> --- a/drivers/gpu/drm/display/drm_bridge_connector.c
> +++ b/drivers/gpu/drm/display/drm_bridge_connector.c
> @@ -673,14 +673,22 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>  		if (!bridge->ycbcr_420_allowed)
>  			connector->ycbcr_420_allowed = false;
>
> -		if (bridge->ops & DRM_BRIDGE_OP_EDID)
> -			bridge_connector->bridge_edid = bridge;
> +		/*
> +		 * Ensure the last bridge declares OP_EDID or OP_MODES or both.
> +		 */
> +		if (bridge->ops & DRM_BRIDGE_OP_EDID || bridge->ops & DRM_BRIDGE_OP_MODES) {
> +			bridge_connector->bridge_edid = NULL;
> +			bridge_connector->bridge_modes = NULL;
> +			if (bridge->ops & DRM_BRIDGE_OP_EDID)
> +				bridge_connector->bridge_edid = bridge;
> +			if (bridge->ops & DRM_BRIDGE_OP_MODES)
> +				bridge_connector->bridge_modes = bridge;
> +		}
>  		if (bridge->ops & DRM_BRIDGE_OP_HPD)
>  			bridge_connector->bridge_hpd = bridge;
>  		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
>  			bridge_connector->bridge_detect = bridge;
> -		if (bridge->ops & DRM_BRIDGE_OP_MODES)
> -			bridge_connector->bridge_modes = bridge;
> +

This does not apply on current drm-misc-next, due to the patch I mentioned
in a previous iteration, now applied as commit 2be300f9a0b6 ("drm/display:
bridge_connector: get/put the stored bridges").

However I'm sorry I have to mention that patch turned out being buggy, so
I've sent a series to apply a corrected version [0]. I suggest watching the
disucssion about the fix series, and if that gets approved rebase on top of
that and adapt your changes.

Sorry about the mess. :(

[0] https://lore.kernel.org/r/20251017-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-v2-0-667abf6d47c0@bootlin.com

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
Re: [PATCH v7 01/18] drm/display: bridge_connector: Ensure last bridge determines EDID/modes detection capabilities
Posted by Damon Ding 1 month, 3 weeks ago 
Hi Luca,

On 10/21/2025 6:31 PM, Luca Ceresoli wrote:
> Hello Damon,
> 
> On Tue Oct 21, 2025 at 4:31 AM CEST, Damon Ding wrote:
>> When multiple bridges are present, EDID detection capability
>> (DRM_BRIDGE_OP_EDID) takes precedence over modes detection
>> (DRM_BRIDGE_OP_MODES). To ensure the above two capabilities are
>> determined by the last bridge in the chain, we handle three cases:
>>
>> Case 1: The later bridge declares only DRM_BRIDGE_OP_MODES
>>   - If the previous bridge declares DRM_BRIDGE_OP_EDID, set
>>     &drm_bridge_connector.bridge_edid to NULL and set
>>     &drm_bridge_connector.bridge_modes to the later bridge.
>>   - Ensure modes detection capability of the later bridge will not
>>     be ignored.
>>
>> Case 2: The later bridge declares only DRM_BRIDGE_OP_EDID
>>   - If the previous bridge declares DRM_BRIDGE_OP_MODES, set
>>     &drm_bridge_connector.bridge_modes to NULL and set
>>     &drm_bridge_connector.bridge_edid to the later bridge.
>>   - Although EDID detection capability has higher priority, this
>>     operation is for balance and makes sense.
>>
>> Case 3: the later bridge declares both of them
>>   - Assign later bridge as &drm_bridge_connector.bridge_edid and
>>     and &drm_bridge_connector.bridge_modes to this bridge.
>>   - Just leave transfer of these two capabilities as before.
>>
>> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
>> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
>> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
>>
>> ---
>>
>> Changes in v7:
>> - As Luca suggested, simplify the code and related comment.
>> ---
>>   drivers/gpu/drm/display/drm_bridge_connector.c | 16 ++++++++++++----
>>   1 file changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
>> index baacd21e7341..7c2936d59517 100644
>> --- a/drivers/gpu/drm/display/drm_bridge_connector.c
>> +++ b/drivers/gpu/drm/display/drm_bridge_connector.c
>> @@ -673,14 +673,22 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>>   		if (!bridge->ycbcr_420_allowed)
>>   			connector->ycbcr_420_allowed = false;
>>
>> -		if (bridge->ops & DRM_BRIDGE_OP_EDID)
>> -			bridge_connector->bridge_edid = bridge;
>> +		/*
>> +		 * Ensure the last bridge declares OP_EDID or OP_MODES or both.
>> +		 */
>> +		if (bridge->ops & DRM_BRIDGE_OP_EDID || bridge->ops & DRM_BRIDGE_OP_MODES) {
>> +			bridge_connector->bridge_edid = NULL;
>> +			bridge_connector->bridge_modes = NULL;
>> +			if (bridge->ops & DRM_BRIDGE_OP_EDID)
>> +				bridge_connector->bridge_edid = bridge;
>> +			if (bridge->ops & DRM_BRIDGE_OP_MODES)
>> +				bridge_connector->bridge_modes = bridge;
>> +		}
>>   		if (bridge->ops & DRM_BRIDGE_OP_HPD)
>>   			bridge_connector->bridge_hpd = bridge;
>>   		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
>>   			bridge_connector->bridge_detect = bridge;
>> -		if (bridge->ops & DRM_BRIDGE_OP_MODES)
>> -			bridge_connector->bridge_modes = bridge;
>> +
> 
> This does not apply on current drm-misc-next, due to the patch I mentioned
> in a previous iteration, now applied as commit 2be300f9a0b6 ("drm/display:
> bridge_connector: get/put the stored bridges").
> 
> However I'm sorry I have to mention that patch turned out being buggy, so
> I've sent a series to apply a corrected version [0]. I suggest watching the
> disucssion about the fix series, and if that gets approved rebase on top of
> that and adapt your changes.
> 
> Sorry about the mess. :(
> 
> [0] https://lore.kernel.org/r/20251017-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-v2-0-667abf6d47c0@bootlin.com
> 
> 

I saw your fix patches before sending this series. I think your patches 
will likely be merged relatively quickly, so I plan to wait until the 
other patches in my patch series are confirmed to be fine, then submit 
v8 version based on the latest bridge_connector driver. :-)

Best regards,
Damon
Re: [PATCH v7 01/18] drm/display: bridge_connector: Ensure last bridge determines EDID/modes detection capabilities
Posted by Heiko Stuebner 22 hours ago 
Am Mittwoch, 22. Oktober 2025, 03:15:52 Mitteleuropäische Normalzeit schrieb Damon Ding:
> Hi Luca,
> 
> On 10/21/2025 6:31 PM, Luca Ceresoli wrote:
> > Hello Damon,
> > 
> > On Tue Oct 21, 2025 at 4:31 AM CEST, Damon Ding wrote:

> > 
> > This does not apply on current drm-misc-next, due to the patch I mentioned
> > in a previous iteration, now applied as commit 2be300f9a0b6 ("drm/display:
> > bridge_connector: get/put the stored bridges").
> > 
> > However I'm sorry I have to mention that patch turned out being buggy, so
> > I've sent a series to apply a corrected version [0]. I suggest watching the
> > disucssion about the fix series, and if that gets approved rebase on top of
> > that and adapt your changes.
> > 
> > Sorry about the mess. :(
> > 
> > [0] https://lore.kernel.org/r/20251017-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-v2-0-667abf6d47c0@bootlin.com
> > 
> > 
> 
> I saw your fix patches before sending this series. I think your patches 
> will likely be merged relatively quickly, so I plan to wait until the 
> other patches in my patch series are confirmed to be fine, then submit 
> v8 version based on the latest bridge_connector driver. :-)

I think with 6.19-rc1 out, now is a great time for v8? :-)

Heiko
Re: [PATCH v7 01/18] drm/display: bridge_connector: Ensure last bridge determines EDID/modes detection capabilities
Posted by Damon Ding 9 hours ago 
Hi Heiko,

On 12/16/2025 9:48 PM, Heiko Stuebner wrote:
> Am Mittwoch, 22. Oktober 2025, 03:15:52 Mitteleuropäische Normalzeit schrieb Damon Ding:
>> Hi Luca,
>>
>> On 10/21/2025 6:31 PM, Luca Ceresoli wrote:
>>> Hello Damon,
>>>
>>> On Tue Oct 21, 2025 at 4:31 AM CEST, Damon Ding wrote:
> 
>>>
>>> This does not apply on current drm-misc-next, due to the patch I mentioned
>>> in a previous iteration, now applied as commit 2be300f9a0b6 ("drm/display:
>>> bridge_connector: get/put the stored bridges").
>>>
>>> However I'm sorry I have to mention that patch turned out being buggy, so
>>> I've sent a series to apply a corrected version [0]. I suggest watching the
>>> disucssion about the fix series, and if that gets approved rebase on top of
>>> that and adapt your changes.
>>>
>>> Sorry about the mess. :(
>>>
>>> [0] https://lore.kernel.org/r/20251017-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-v2-0-667abf6d47c0@bootlin.com
>>>
>>>
>>
>> I saw your fix patches before sending this series. I think your patches
>> will likely be merged relatively quickly, so I plan to wait until the
>> other patches in my patch series are confirmed to be fine, then submit
>> v8 version based on the latest bridge_connector driver. :-)
> 
> I think with 6.19-rc1 out, now is a great time for v8? :-)
> 

Agreed! Luca's patches have been merged. I will reconfirm these commits 
on the latest branch and update v8 in a few day. :-)

Best regards,
Damon

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