Re: [PATCH RESEND v5 01/25] drm/msm/dp: introduce stream_id for each DP panel

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

On 7/12/2026 7:11 PM, Dmitry Baryshkov wrote:
> On Mon, Jun 29, 2026 at 10:14:22PM +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
> 
> You are not creating IDs.
> 
Got it. Will modify it next patchset.
>> panel which shall be dynamically assigned to actual stream IDs by the MST
>> path. For SST, default this to stream 0.
>>
>> In the MST path, panels are dynamically assigned to actual stream IDs at
>> stream enable time by the MST layer.
>>
>> 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    | 67 +++++++++++++++++++++++--------------
>>   drivers/gpu/drm/msm/dp/dp_ctrl.h    |  2 +-
>>   drivers/gpu/drm/msm/dp/dp_display.c |  2 +-
>>   drivers/gpu/drm/msm/dp/dp_panel.c   |  1 +
>>   drivers/gpu/drm/msm/dp/dp_panel.h   | 11 ++++++
>>   5 files changed, 55 insertions(+), 28 deletions(-)
>>
>> @@ -2188,38 +2188,39 @@ static bool msm_dp_ctrl_send_phy_test_pattern(struct msm_dp_ctrl_private *ctrl)
>>   	return success;
>>   }
>>   
>> -static int msm_dp_ctrl_on_pixel_clk(struct msm_dp_ctrl_private *ctrl, unsigned long pixel_rate)
>> +static int msm_dp_ctrl_on_pixel_clk(struct msm_dp_ctrl_private *ctrl, unsigned long pixel_rate,
>> +				    enum msm_dp_stream_id stream_id)
>>   {
>>   	int ret;
>>   
>> -	ret = clk_set_rate(ctrl->pixel_clk, pixel_rate * 1000);
>> +	ret = clk_set_rate(ctrl->pixel_clk[stream_id], pixel_rate * 1000);
>>   	if (ret) {
>>   		DRM_ERROR("Failed to set pixel clock rate. ret=%d\n", ret);
>>   		return ret;
>>   	}
>>   
>> -	if (WARN_ON_ONCE(ctrl->stream_clks_on))
>> +	if (WARN_ON_ONCE(ctrl->stream_clks_on[stream_id]))
>>   		return 0;
> 
> Is it an error, defensive coding, DT mismatch or something else? Why are
> we warning the users _and_ returning success here?
> 
This is primarily defensive code. The normal execution flow is not 
expected to reach this path, so we only print a warning here.
>>   
>> -	ret = clk_prepare_enable(ctrl->pixel_clk);
>> +	ret = clk_prepare_enable(ctrl->pixel_clk[stream_id]);
>>   	if (ret) {
>>   		DRM_ERROR("Failed to start pixel clocks. ret=%d\n", ret);
>>   		return ret;
>>   	}
>> -	ctrl->stream_clks_on = true;
>> +	ctrl->stream_clks_on[stream_id] = true;
>>   
>>   	return ret;
>>   }
>>   
>