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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Thu, 8 Sep 2022 11:05:03 +0800
From:   Jason Yen <jason.yen@...adetech.corp-partner.google.com>
To:     Rock Chiu <rock.chiu@...adetech.corp-partner.google.com>
Cc:     Doug Anderson <dianders@...omium.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/bridge: ps8640: Add double reset T4 and T5 to
 power-on sequence

The chip is functional ready 200ms after the chip reset. The 200ms is
mainly for loading firmware from spi rom.

-Jason


On Thu, Sep 8, 2022 at 8:32 AM Rock Chiu
<rock.chiu@...adetech.corp-partner.google.com> wrote:
>
> + Jason.
>
> -Rock
>
> Doug Anderson <dianders@...omium.org> 於 2022年8月30日 週二 清晨5:49寫道：
> >
> > Hi,
> >
> > On Mon, Aug 22, 2022 at 9:33 AM Doug Anderson <dianders@...omium.org> wrote:
> > >
> > > Hi,
> > >
> > > On Thu, Aug 18, 2022 at 8:03 AM Doug Anderson <dianders@...omium.org> wrote:
> > > >
> > > > Hi,
> > > >
> > > > On Wed, Aug 17, 2022 at 8:22 PM Hsin-Yi Wang <hsinyi@...omium.org> wrote:
> > > > >
> > > > > On Thu, Aug 18, 2022 at 11:19 AM Rock Chiu
> > > > > <rock.chiu@...adetech.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