Re: [PATCH v4 13/39] drm/msm/dp: introduce stream_id for each DP panel

[Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>]

On Fri, Apr 10, 2026 at 05:33:48PM +0800, Yongxing Mou wrote:
> From: Abhinav Kumar <quic_abhinavk@quicinc.com>
> 
> With MST, each DP controller can handle multiple streams.
> There shall be one dp_panel for each stream but the dp_display
> object shall be shared among them. To represent this abstraction,
> create a stream_id for each DP panel which shall be set by the
> MST stream. For SST, default this to stream 0.
> 
> Use the stream ID to control the pixel clock of that respective
> stream by extending the clock handles and state tracking of the
> DP pixel clock to an array of max supported streams. The maximum
> streams currently is 4.
> 
> Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
> Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
> ---
>  drivers/gpu/drm/msm/dp/dp_ctrl.c    | 57 +++++++++++++++++++++++--------------
>  drivers/gpu/drm/msm/dp/dp_ctrl.h    |  2 +-
>  drivers/gpu/drm/msm/dp/dp_display.c | 24 ++++++++++++++--
>  drivers/gpu/drm/msm/dp/dp_display.h |  2 ++
>  drivers/gpu/drm/msm/dp/dp_panel.h   | 11 +++++++
>  5 files changed, 71 insertions(+), 25 deletions(-)
> @@ -2735,9 +2740,17 @@ static int msm_dp_ctrl_clk_init(struct msm_dp_ctrl *msm_dp_ctrl)
>  	if (rc)
>  		return rc;
>  
> -	ctrl->pixel_clk = devm_clk_get(dev, "stream_pixel");
> -	if (IS_ERR(ctrl->pixel_clk))
> -		return PTR_ERR(ctrl->pixel_clk);
> +	for (i = DP_STREAM_0; i < DP_STREAM_MAX; i++) {
> +		ctrl->pixel_clk[i] = devm_clk_get(dev, pixel_clks[i]);
> +
> +		if (i == 0 && IS_ERR(ctrl->pixel_clk[i]))
> +			return PTR_ERR(ctrl->pixel_clk[i]);
> +
> +		if (IS_ERR(ctrl->pixel_clk[i])) {
> +			DRM_DEBUG_DP("stream %d pixel clock not exist", i);
> +			break;
> +		}

Almost missed it. If it is -EPROBE_DEFER, we must return an error. In
fact, I'd rather check for -ENOENT (or is it -ENODEV?) and pass all
other errors to the caller.

> +	}
>  
>  	return 0;
>  }

-- 
With best wishes
Dmitry