[PATCH] drm/msm/dp: support setting the DP subconnector type

[Dmitry Baryshkov]

On 08/09/2023 00:34, Stephen Boyd wrote:
> Quoting Dmitry Baryshkov (2023-09-03 15:24:32)
>> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
>> index 97ba41593820..1cb54f26f5aa 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_panel.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_panel.c
>> @@ -162,6 +162,11 @@ int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
>>                  }
>>          }
>>
>> +       rc = drm_dp_read_downstream_info(panel->aux, dp_panel->dpcd,
>> +                                        dp_panel->downstream_ports);
>> +       if (rc)
>> +               return rc;
> 
> I haven't been able to test it yet, but I think with an apple dongle
> we'll never populate the 'downstream_ports' member if the HDMI cable is
> not connected when this runs. That's because this function bails out
> early before trying to read the downstream ports when there isn't a
> sink. Perhaps we need to read it again when an hpd_irq comes in, or we
> need to read it before bailing out from here?

I don't have an Apple dongle here. But I'll run a check with first 
connecting the dongle and plugging the HDMI afterwards.

However my expectation based on my previous tests is that we only get 
here when the actual display is connected.

-- 
With best wishes
Dmitry