linux-kernel - Re: [alsa-devel] [PATCH] ASoC: cs42l56: Fix misuse of regmap_update

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Message-ID: <fc0ed157-8514-47cc-9fbb-235968541a36@EX3.ad.cirrus.com>
Date:   Thu, 1 Dec 2016 08:57:54 -0600
From:   Brian Austin <brian.austin@...rus.com>
To:     Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
CC:     Florian Vaussard <florian.vaussard@...il.com>,
        Brian Austin <brian.austin@...rus.com>,
        Paul Handrigan <Paul.Handrigan@...rus.com>,
        <alsa-devel@...a-project.org>, Liam Girdwood <lgirdwood@...il.com>,
        <linux-kernel@...r.kernel.org>,
        Florian Vaussard <florian.vaussard@...g-vd.ch>,
        Takashi Iwai <tiwai@...e.com>, Mark Brown <broonie@...nel.org>
Subject: Re: [alsa-devel] [PATCH] ASoC: cs42l56: Fix misuse of
 regmap_update_bits

On Thu, 1 Dec 2016, Charles Keepax wrote:

> On Tue, Nov 29, 2016 at 06:10:49PM +0100, Florian Vaussard wrote:
> > Using regmap_update_bits(..., mask, 1) with 'mask' following (1 << k)
> > and k greater than 0 is wrong. Indeed, _regmap_update_bits will perform
> > (mask & 1), which results in 0 if LSB of mask is 0. Thus the call
> > regmap_update_bits(..., mask, 1) is in reality equivalent to
> > regmap_update_bits(..., mask, 0).
> > 
> > In such a case, the correct use is regmap_update_bits(..., mask, mask).
> > 
> > This driver is performing such a mistake with the CS42L56_AIN*_REF_MASK
> > masks, which equal 0x10, 0x20, 0x40 and 0x80. Fix the driver to make it
> > consistent with the API. Please note that this change is untested,
> > as I do not have this piece of hardware. Testers are welcome!
> > 
> > Signed-off-by: Florian Vaussard <florian.vaussard@...g-vd.ch>
> > ---
> 
> Looks good to me:
> 
> Reviewed-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
> 
> Thanks,
> Charles
> 
Acked-by: Brian Austin <brian.austin@...rus.com>

Thanks,
Brian