Re: [PATCH RESEND v5 13/25] drm/msm/dp: replace power_on with active_stream_cnt for dp_display

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

On 7/13/2026 2:51 AM, Dmitry Baryshkov wrote:
> On Mon, Jun 29, 2026 at 10:14:34PM +0800, Yongxing Mou wrote:
>> From: Abhinav Kumar <quic_abhinavk@quicinc.com>
>>
>> For DP MST, the link clock and power domain resources stay on until
>> both streams have been disabled OR we receive hotplug. Introduce an
>> active_stream_cnt to track the number of active streams and necessary
>> state handling. Replace the power_on variable with active_stream_cnt
>> as power_on boolean works only for a single stream.
> 
> Last two phrases are redundat. Drop the "Introduce..." one.
> 
>>
>> 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_audio.c   |  2 +-
>>   drivers/gpu/drm/msm/dp/dp_display.c | 28 +++++++++++++++++-----------
>>   drivers/gpu/drm/msm/dp/dp_display.h |  2 +-
>>   3 files changed, 19 insertions(+), 13 deletions(-)
>>
>> @@ -670,14 +670,10 @@ static int msm_dp_display_enable(struct msm_dp_display_private *dp,
>>   	struct msm_dp *msm_dp_display = &dp->msm_dp_display;
>>   
>>   	drm_dbg_dp(dp->drm_dev, "sink_count=%d\n", dp->link->sink_count);
>> -	if (msm_dp_display->power_on) {
>> -		drm_dbg_dp(dp->drm_dev, "Link already setup, return\n");
>> -		return 0;
>> -	}
>>   
>>   	rc = msm_dp_ctrl_on_stream(dp->ctrl, msm_dp_panel, msm_dp_display->mst_active);
>> -	if (!rc)
>> -		msm_dp_display->power_on = true;
>> +
>> +	msm_dp_display->active_stream_cnt++;
> 
> Current power_on prevents from calling msm_dp_ctrl_on_stream() several
> times. How is it prevented after the change?
> 
I think we don't need to prevent it. It call drom .atomic_enable() and 
it should not call twice in SST case.
>>   
>>   	return rc;
>>   }
>> @@ -726,14 +722,14 @@ static int msm_dp_display_disable(struct msm_dp_display_private *dp,
>>   {
>>   	struct msm_dp *msm_dp_display = &dp->msm_dp_display;
>>   
>> -	if (!msm_dp_display->power_on)
>> +	if (!msm_dp_display->active_stream_cnt)
>>   		return 0;
>>   
>>   	msm_dp_panel_disable_vsc_sdp(msm_dp_panel);
>>   
>>   	msm_dp_ctrl_off_pixel_clk(dp->ctrl, msm_dp_panel->stream_id);
>>   
>> -	msm_dp_display->power_on = false;
>> +	msm_dp_display->active_stream_cnt--;
>>   
>>   	drm_dbg_dp(dp->drm_dev, "sink count: %d\n", dp->link->sink_count);
>>   	return 0;
>> @@ -850,10 +846,10 @@ void msm_dp_snapshot(struct msm_disp_state *disp_state, struct msm_dp *dp)
>>   	 * if we are reading registers we need the link clocks to be on
>>   	 * however till DP cable is connected this will not happen as we
>>   	 * do not know the resolution to power up with. Hence check the
>> -	 * power_on status before dumping DP registers to avoid crash due
>> +	 * active_stream_cnt status before dumping DP registers to avoid crash due
>>   	 * to unclocked access
>>   	 */
>> -	if (!dp->power_on)
>> +	if (!dp->active_stream_cnt)
>>   		return;
>>   
>>   	msm_disp_snapshot_add_block(disp_state, msm_dp_display->ahb_len,
>> @@ -1535,6 +1531,11 @@ void msm_dp_display_disable_helper(struct msm_dp *msm_dp_display,
>>   
>>   	dp = container_of(msm_dp_display, struct msm_dp_display_private, msm_dp_display);
>>   
>> +	if (!msm_dp_display->active_stream_cnt) {
>> +		drm_dbg_dp(dp->drm_dev, "no active streams\n");
>> +		return;
>> +	}
> 
> If you get here, there was at least one active stream, wasn't it?
> 
Emm yes..
>> +
>>   	msm_dp_ctrl_push_vcpf(dp->ctrl, msm_dp_panel);
>>   	msm_dp_ctrl_mst_stream_channel_slot_setup(dp->ctrl);
>>   	msm_dp_ctrl_mst_send_act(dp->ctrl, msm_dp_panel);
>> @@ -1555,6 +1556,11 @@ void msm_dp_display_unprepare(struct msm_dp *msm_dp_display)
>>   
>>   	dp = container_of(msm_dp_display, struct msm_dp_display_private, msm_dp_display);
>>   
>> +	if (msm_dp_display->active_stream_cnt) {
>> +		drm_dbg_dp(dp->drm_dev, "stream still active, return\n");
>> +		return;
> 
> Why?
> 
Here, unprepare is only called when the last active stream is also being 
disabled.
> General comment. You are not just replacing power_on with
> active_stream_cnt. You are also introducing sequence changes, but it is
> not covered in the cover letter. It's not clear, why those changes are
> legitimage or why they are required.
> 
Got it. Will modify the commit message.. thanks~
>> +	}
>> +
>>   	/* dongle is still connected but sinks are disconnected */
>>   	if (dp->link->sink_count == 0)
>>   		msm_dp_link_psm_config(dp->link, &dp->panel->link_info, true);
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
>> index 55ffa22bb233..75dc40261723 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.h
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
>> @@ -18,7 +18,7 @@ struct msm_dp {
>>   	struct drm_bridge *next_bridge;
>>   	struct drm_bridge *bridge;
>>   	bool audio_enabled;
>> -	bool power_on;
>> +	u32 active_stream_cnt;
>>   	bool mst_active;
>>   	unsigned int connector_type;
>>   	bool is_edp;
>>
>> -- 
>> 2.43.0
>>
>