Re: [PATCH v6 03/10] drm/msm/dp: Read DPCD and sink count in bridge detect()

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

On 25/05/2026 15:32, Konrad Dybcio wrote:
> On 5/24/26 12:33 PM, Dmitry Baryshkov wrote:
>> From: Jessica Zhang <jessica.zhang@oss.qualcomm.com>
>>
>> Instead of relying on the link_ready flag to specify if DP is connected,
>> read the DPCD bits and get the sink count to accurately detect if DP is
>> connected.
>>
>> Signed-off-by: Jessica Zhang <jessica.zhang@oss.qualcomm.com>
>> Tested-by: Val Packett <val@packett.cool> # x1e80100-dell-latitude-7455
>> Tested-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com> # Hamoa IOT EVK, QCS8300 Ride
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
>> ---
>>   drivers/gpu/drm/msm/dp/dp_display.c | 63 +++++++++++++++++++++++++++++++++++++
>>   drivers/gpu/drm/msm/dp/dp_drm.c     | 20 ------------
>>   drivers/gpu/drm/msm/dp/dp_drm.h     |  2 ++
>>   3 files changed, 65 insertions(+), 20 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 1dd168acbbc3..97c4752005c0 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -1152,6 +1152,69 @@ static int msm_dp_hpd_event_thread_start(struct msm_dp_display_private *msm_dp_p
>>   	return 0;
>>   }
>>   
>> +/**
>> + * msm_dp_bridge_detect - callback to determine if connector is connected
>> + *
>> + * @bridge: Pointer to drm bridge structure
>> + * @connector: Pointer to drm connector structure
>> + *
>> + * Returns: where there is a display connected to the DPTX (returning
> 
> 		whether?

yep

> 
> Otherwise, if keeping msm_dp_aux_enable_xfers(true) is intentional
> in bailout cases:

In the non-error bailouts, yes. I might want to change that later, but 
for now it's expected this way.

> 
> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
> 
> Konrad


-- 
With best wishes
Dmitry