linux-kernel - Re: ALSA: intel8x0: div by zero in snd_intel8x0

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Message-ID: <CAMo8Bf+bGujLN7H5yBqy-AkPCN7LgfmGSiWEGdjW6ZWeFoXs9A@mail.gmail.com>
Date:   Thu, 8 Jul 2021 01:41:50 -0700
From:   Max Filippov <jcmvbkbc@...il.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        alsa-devel@...a-project.org, Leon Romanovsky <leon@...nel.org>,
        Takashi Iwai <tiwai@...e.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Subject: Re: ALSA: intel8x0: div by zero in snd_intel8x0_update()

On Thu, Jul 8, 2021 at 12:13 AM Takashi Iwai <tiwai@...e.de> wrote:
> On Wed, 07 Jul 2021 22:33:22 +0200,
> Max Filippov wrote:
> >
> > On Wed, Jul 7, 2021 at 11:14 AM Takashi Iwai <tiwai@...e.de> wrote:
> > > On Wed, 07 Jul 2021 19:50:07 +0200, Max Filippov wrote:
> > > > It didn't change anything in my case. My further observation is that
> > > > the snd_intel8x0_update is called before the ichdev->prepared
> > > > is set to one and as a result IRQ is apparently never cleared.
> > >
> > > So it's broken in anyway no matter whether
> > > intel8x0_measure_ac97_clock() is called or not, right?
> >
> > The change that you suggested didn't eliminate the call to
> > intel8x0_measure_ac97_clock, it's still called and an interrupt
> > flood happens at the same place.
>
> Ah I see the point.  Then the fix would be a oneliner like below.
>
>
> Takashi
>
> --- a/sound/pci/intel8x0.c
> +++ b/sound/pci/intel8x0.c
> @@ -694,7 +694,7 @@ static inline void snd_intel8x0_update(struct intel8x0 *chip, struct ichdev *ich
>         int status, civ, i, step;
>         int ack = 0;
>
> -       if (!ichdev->prepared || ichdev->suspended)
> +       if (!(ichdev->prepared || ichdev->in_measurement) || ichdev->suspended)

There's no ichdev::in_measurement, but if replaced with
chip->in_measurement it indeed fixes my issue.
So with this change:
Tested-by: Max Filippov <jcmvbkbc@...il.com>

-- 
Thanks.
-- Max