[PATCH] Revert "drm/msm/dp: use drm_bridge_hpd_notify() to report HPD status changes"

[Dmitry Baryshkov]

On Wed, 28 Feb 2024 at 11:50, Johan Hovold <johan at kernel.org> wrote:
>
> On Tue, Feb 27, 2024 at 02:11:56PM -0800, Abhinav Kumar wrote:
> > On 2/27/2024 2:08 PM, Dmitry Baryshkov wrote:
> > > This reverts commit e467e0bde881 ("drm/msm/dp: use
> > > drm_bridge_hpd_notify() to report HPD status changes").
> > >
> > > The commit changed the way how the MSM DP driver communicates
> > > HPD-related events to the userspace. The mentioned commit made some of
> > > the HPD events being reported earlier. This way userspace starts poking
> > > around. It interacts in a bad way with the dp_bridge_detect and the
> > > driver's state machine, ending up either with the very long delays
> > > during hotplug detection or even inability of the DP driver to report
> > > the display as connected.
> > >
> > > A proper fix will involve redesigning of the HPD handling in the MSM DP
> > > driver. It is underway, but it will be intrusive and can not be thought
> > > about as a simple fix for the issue. Thus, revert the offending commit.
> >
> > Yes, for fixing this on 6.9 I am fine with this.
>
> Since this is a regression in 6.8-rc1, I hope you meant to say 6.8 here?

In the worst case it will land to 6.8.x via the stable tree process.

>
> > I hope there were not other changes which were built on top of this. So
> > it will be better if we retest internal HPD case as well with this.
> >
> > We will do that in a day or two and give Tested-by.
>
> Johan



-- 
With best wishes
Dmitry