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

[Dmitry Baryshkov]

On 25/05/2026 15:32, Konrad Dybcio wrote:
> On 5/24/26 12:33 PM, Dmitry Baryshkov wrote:
> > From: Jessica Zhang <jessica.zhang@xxxxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxxxx>
> > Tested-by: Val Packett <val@xxxxxxxxxxxx> # x1e80100-dell-latitude-7455
> > Tested-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx> # Hamoa IOT EVK, QCS8300 Ride
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
> > ---
> >   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@xxxxxxxxxxxxxxxx>
>
> Konrad


--
With best wishes
Dmitry