linux-kernel - Re: [PATCH 2/2] ASoC: codec: wm8960: Relax bit clock computation when using PLL

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Message-ID: <CAK8P3a3n-pzaPkyximnW8kt8HXS=gjtGtf_j=at-1Ea=gbkD-A@mail.gmail.com>
Date:   Fri, 21 Apr 2017 16:44:25 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Daniel Baluta <daniel.baluta@....com>
Cc:     Mark Brown <broonie@...nel.org>, tiwai@...e.com,
        Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        patches@...nsource.wolfsonmicro.com, alsa-devel@...a-project.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] ASoC: codec: wm8960: Relax bit clock computation when
 using PLL

On Fri, Apr 21, 2017 at 3:07 PM, Daniel Baluta <daniel.baluta@....com> wrote:
> Bitclk is derived from sysclk using bclk_divs.
> Sysclk can be derived in two ways:
>         (1) directly from MLCK
>         (2) MCLK via PLL
>
> Commit 3c01b9ee2ab9d0d ("ASoC: codec: wm8960: Relax bit clock
> computation")
> relaxed bitclk computation when sysclk is directly derived from MCLK.
>
> Lets do the same thing when sysclk is derived via PLL.
>
> Signed-off-by: Daniel Baluta <daniel.baluta@....com>
> ---
> Here, I forced the following harmless initialization:
>
>         *sysclk_idx = *dac_idx = *bclk_idx = -1;
>
> otherwise I would trigger a gcc false positive warning:
>
> sound/soc/codecs/wm8960.c: In function 'wm8960_configure_clocking':
> sound/soc/codecs/wm8960.c:810:46: warning: 'j' may be used uninitialized
> in this function [-Wmaybe-uninitialized]
>   snd_soc_update_bits(codec, WM8960_CLOCK1, 0x7 << 6, j << 6);
>                                             ~~^~~~
> sound/soc/codecs/wm8960.c:806:44: warning: 'i' may be used uninitialized
> in this function [-Wmaybe-uninitialized]
> snd_soc_update_bits(codec, WM8960_CLOCK1, 3 << 1, i << 1);
>                                           ~~^~~~

I saw the same warning earlier, but it was gone after the rework
I posted the other day. Please try if that works for you as well, I think
that would be better than a bogus initialization.

       Arnd