Re: [PATCH v3 34/38] drm/msm: initialize DRM MST encoders for DP controllers

[Yongxing Mou <yongxing.mou@oss.qualcomm.com>]

On 8/27/2025 2:55 AM, Dmitry Baryshkov wrote:
> On Mon, Aug 25, 2025 at 10:16:20PM +0800, Yongxing Mou wrote:
>> From: Abhinav Kumar <quic_abhinavk@quicinc.com>
>>
>> Initialize a DPMST encoder for each  MST capable DP controller
>> and the number of encoders it supports depends on the number
>> of streams it supports.
>>
>> Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
>> Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  2 ++
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c     | 23 ++++++++++++++++++++++-
>>   drivers/gpu/drm/msm/dp/dp_mst_drm.h         |  2 --
>>   drivers/gpu/drm/msm/msm_drv.h               | 13 +++++++++++++
>>   4 files changed, 37 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>> index ca1ca2e51d7ead0eb34b27f3168e6bb06a71a11a..2eb4c39b111c1d8622e09e78ffafef017e28bbf6 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
>> @@ -28,6 +28,7 @@
>>    * @h_tile_instance:    Controller instance used per tile. Number of elements is
>>    *                      based on num_of_h_tiles
>>    * @is_cmd_mode		Boolean to indicate if the CMD mode is requested
>> + * @stream_id		stream id for which the interface needs to be acquired
>>    * @vsync_source:	Source of the TE signal for DSI CMD devices
>>    */
>>   struct msm_display_info {
>> @@ -35,6 +36,7 @@ struct msm_display_info {
>>   	uint32_t num_of_h_tiles;
>>   	uint32_t h_tile_instance[MAX_H_TILES_PER_DISPLAY];
>>   	bool is_cmd_mode;
>> +	int stream_id;
>>   	enum dpu_vsync_source vsync_source;
>>   };
>>   
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> index 12dcb32b472497f9e59619db4e810abfbf610c7c..0b9d9207f4f69e0d0725ff265c624828b5816a8b 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> @@ -653,7 +653,8 @@ static int _dpu_kms_initialize_displayport(struct drm_device *dev,
>>   	struct msm_display_info info;
>>   	bool yuv_supported;
>>   	int rc;
>> -	int i;
>> +	int i, stream_id;
>> +	int stream_cnt;
>>   
>>   	for (i = 0; i < ARRAY_SIZE(priv->kms->dp); i++) {
>>   		if (!priv->kms->dp[i])
>> @@ -676,6 +677,26 @@ static int _dpu_kms_initialize_displayport(struct drm_device *dev,
>>   			DPU_ERROR("modeset_init failed for DP, rc = %d\n", rc);
>>   			return rc;
>>   		}
>> +
>> +		stream_cnt = msm_dp_get_mst_max_stream(priv->kms->dp[i]);
>> +
>> +		if (stream_cnt > 1) {
>> +			for (stream_id = 0; stream_id < stream_cnt; stream_id++) {
>> +				info.stream_id = stream_id;
>> +				encoder = dpu_encoder_init(dev, DRM_MODE_ENCODER_DPMST, &info);
>> +				if (IS_ERR(encoder)) {
>> +					DPU_ERROR("encoder init failed for dp mst display\n");
>> +					return PTR_ERR(encoder);
>> +				}
>> +
>> +				rc = msm_dp_mst_drm_bridge_init(priv->kms->dp[i], encoder);
> 
> This is an implementation detail. We should be asking to init MST, which
> might or might not be a bridge.
> 
Got it. How about renaming it to msm_dp_mst_attach_encoder?
>> +				if (rc) {
>> +					DPU_ERROR("dp mst bridge %d init failed, %d\n",
> 
> DP, MST, no 'bridge'.
> 
Got it. Thanks.
>> +						  stream_id, rc);
>> +					continue;
>> +				}
>> +			}
>> +		}
>>   	}
>>   
>>   	return 0;
>> diff --git a/drivers/gpu/drm/msm/dp/dp_mst_drm.h b/drivers/gpu/drm/msm/dp/dp_mst_drm.h
>> index 8fe6cbbe741da4abb232256b3a15ba6b16ca4f3e..d73e3f908439094532e88945ed4d41ed092051c9 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_mst_drm.h
>> +++ b/drivers/gpu/drm/msm/dp/dp_mst_drm.h
>> @@ -82,8 +82,6 @@ struct msm_dp_mst_connector {
>>   	struct msm_dp_panel *dp_panel;
>>   };
>>   
> 
>> -int msm_dp_mst_drm_bridge_init(struct msm_dp *dp, struct drm_encoder *encoder);
>> -
> 
> Squash this and the next chunks to the corresponding patches.
> 
Will rework it.
>>   int msm_dp_mst_init(struct msm_dp *dp_display, u32 max_streams, struct drm_dp_aux *drm_aux);
>>   
>>   void msm_dp_mst_display_hpd_irq(struct msm_dp *dp_display);
>> diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
>> index 985db9febd98e35dfed51d39dac1a522abe5a351..3e64ec7b7dbe1d1107e85def9aa80277131f40bf 100644
>> --- a/drivers/gpu/drm/msm/msm_drv.h
>> +++ b/drivers/gpu/drm/msm/msm_drv.h
>> @@ -363,6 +363,9 @@ bool msm_dp_needs_periph_flush(const struct msm_dp *dp_display,
>>   			       const struct drm_display_mode *mode);
>>   bool msm_dp_wide_bus_available(const struct msm_dp *dp_display);
>>   
>> +int msm_dp_get_mst_max_stream(struct msm_dp *dp_display);
>> +int msm_dp_mst_drm_bridge_init(struct msm_dp *dp_display, struct drm_encoder *encoder);
>> +
>>   #else
>>   static inline int __init msm_dp_register(void)
>>   {
>> @@ -379,6 +382,16 @@ static inline int msm_dp_modeset_init(struct msm_dp *dp_display,
>>   	return -EINVAL;
>>   }
>>   
>> +static inline int msm_dp_get_mst_max_stream(struct msm_dp *dp_display)
>> +{
>> +	return -EINVAL;
>> +}
>> +
>> +static inline int msm_dp_mst_drm_bridge_init(struct msm_dp *dp_display, struct drm_encoder *encoder)
>> +{
>> +	return -EINVAL;
>> +}
>> +
>>   static inline void msm_dp_snapshot(struct msm_disp_state *disp_state, struct msm_dp *dp_display)
>>   {
>>   }
>>
>> -- 
>> 2.34.1
>>
>