[PATCH 17/17] drm/msm/dp: allow YUV420 mode for DP connector when VSC SDP supported

[Abhinav Kumar]

On 1/25/2024 2:05 PM, Dmitry Baryshkov wrote:
> On 25/01/2024 21:38, Paloma Arellano wrote:
>> All the components of YUV420 over DP are added. Therefore, let's mark the
>> connector property as true for DP connector when the DP type is not eDP
>> and when VSC SDP is supported.
>>
>> Signed-off-by: Paloma Arellano <quic_parellan at quicinc.com>
>> ---
>>   drivers/gpu/drm/msm/dp/dp_display.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c 
>> b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 4329435518351..97edd607400b8 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -370,11 +370,14 @@ static int dp_display_process_hpd_high(struct 
>> dp_display_private *dp)
>>       dp_link_process_request(dp->link);
>> -    if (!dp->dp_display.is_edp)
>> +    if (!dp->dp_display.is_edp) {
>> +        if (dp_panel_vsc_sdp_supported(dp->panel))
>> +            dp->dp_display.connector->ycbcr_420_allowed = true;
> 
> Please consider fixing a TODO in drm_bridge_connector_init().
> 

I am not totally clear if that TODO can ever go for DP/HDMI usage of 
drm_bridge_connector.

We do not know if the sink supports VSC SDP till we read the DPCD and 
till we know that sink supports VSC SDP, there is no reason to mark the 
YUV modes as supported. This is the same logic followed across vendors.

drm_bride_connector_init() happens much earlier than the point where we 
read DPCD. The only thing which can be done is perhaps add some callback 
to update_ycbcr_420_allowed once DPCD is read. But I don't think its 
absolutely necessary to have a callback just for this.

>>           drm_dp_set_subconnector_property(dp->dp_display.connector,
>>                            connector_status_connected,
>>                            dp->panel->dpcd,
>>                            dp->panel->downstream_ports);
>> +    }
>>       edid = dp->panel->edid;
>