[PATCH] drm/bridge: ps8640: Add double reset T4 and T5 to power-on sequence

[Doug Anderson]

Hi,

On Mon, Aug 22, 2022 at 9:33 AM Doug Anderson <dianders at chromium.org> wrote:
>
> Hi,
>
> On Thu, Aug 18, 2022 at 8:03 AM Doug Anderson <dianders at chromium.org> wrote:
> >
> > Hi,
> >
> > On Wed, Aug 17, 2022 at 8:22 PM Hsin-Yi Wang <hsinyi at chromium.org> wrote:
> > >
> > > On Thu, Aug 18, 2022 at 11:19 AM Rock Chiu
> > > <rock.chiu at paradetech.corp-partner.google.com> wrote:
> > > >
> > > > How does T4/T5  impact the real case? We talked previously the T4/T5
> > > > shouldn't cause user impact.
> > > > Do we have testing data from ODM?
> > > >
> > > Please leave comments below the previous comment's headline.
> > >
> > > I'm confused. The reason I upstreamed this patch is because this is in
> > > your application note and you asked us to help upstream it. Now do you
> > > mean that we don't need T4 and T5?
> >
> > I think Rock is asking what problems the extra delay is causing. In
> > other words: why do we care about keeping these delays short?
> >
> > The answer is that it affects boot speed and also resume speed of
> > devices. Adding these two delays here means that there's an extra 100
> > ms before the user can see something on the screen. That may not seem
> > like a lot, but those kinds of delays add up quickly. At least on
> > Chromebooks, booting quickly is always a big goal.
>
> While I'm not very happy with this change and I don't really
> understand why these delays need to be so long, if folks are really
> certain that we need them and can't make them shorter then I guess we
> can land it. I'll wait a few more days in case anyone wants to chime
> in with their thoughts.

I'll continue to grumble, but I did push it.

55453c0914d9 drm/bridge: ps8640: Add double reset T4 and T5 to power-on sequence

I pushed to "drm-misc-next" and not "drm-misc-fixes". It doesn't feel
massively urgent since apparently we've been without the
"double-reset" for years and having the extra bake time feels like the
better way to lean.

-Doug