linux-kernel - Re: [PATCH] Input: st1232 - increase "wait ready" timeout

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Message-ID: <CAMuHMdUbegj+VOVucw+qs5j=QSf3-Sez2-sVZBFD55-wSwMFLg@mail.gmail.com>
Date:   Wed, 29 Sep 2021 19:40:12 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     John Keeping <john@...anate.com>
Cc:     linux-input <linux-input@...r.kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Input: st1232 - increase "wait ready" timeout

On Wed, Sep 29, 2021 at 5:26 PM John Keeping <john@...anate.com> wrote:
> I have a ST1633 touch controller which fails to probe due to a timeout
> waiting for the controller to become ready.  Increasing the minimum
> delay to 100ms ensures that the probe sequence completes successfully.
>
> The ST1633 datasheet says nothing about the maximum delay here and the
> ST1232 I2C protocol document says "wait until" with no notion of a
> timeout.
>
> Since this only runs once during probe, being generous with the timout
> seems reasonable and most likely the device will become ready
> eventually.
>
> (It may be worth noting that I saw this issue with a PREEMPT_RT patched
> kernel which probably has tighter wakeups from usleep_range() than other
> preemption models.)
>
> Fixes: f605be6a57b4 ("Input: st1232 - wait until device is ready before reading resolution")
> Signed-off-by: John Keeping <john@...anate.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds