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

[Dmitry Baryshkov]

On Tue, Apr 07, 2026 at 10:35:49AM +0800, Yongxing Mou wrote:
> 
> 
> 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@xxxxxxxxxxx>
> > > 
> > > 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@xxxxxxxxxxx>
> > > Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> > > ---
> > >   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?

Sure


-- 
With best wishes
Dmitry