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

[Johan Hovold]

On Wed, Feb 28, 2024 at 01:08:04PM +0200, Dmitry Baryshkov wrote:
> 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.

This is a fix for a user-visible regression that was reported formally
two weeks ago and informally (e.g. to you) soon after rc1 came out, and
which now also has an identified cause and an analysis of the problem.
And we're at rc6 so there should be no reason to delay fixing this (e.g.
even if you want to run some more tests for a couple of days).

Johan