linux-kernel - Re: [PATCH] ASoC: codecs: use SNDRV_PCM_FMTBIT

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Date:	Tue, 26 May 2015 16:09:09 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	"Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
Cc:	"alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	patches@...nsource.wolfsonmicro.com,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Daniel Mack <daniel@...que.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>,
	Matt Reimer <mreimer@...systems.com>
Subject: Re: [PATCH] ASoC: codecs: use SNDRV_PCM_FMTBIT_* for format bitmask

At Tue, 26 May 2015 16:03:17 +0200,
Maciej S. Szmigiero wrote:
> 
> Hello Takashi,
> 
> W dniu 26.05.2015 07:29, Takashi Iwai pisze:
> > At Sat, 23 May 2015 18:32:29 +0200,
> > Maciej S. Szmigiero wrote:
> >>
> >> snd_soc_pcm_stream.formats is a bitmask of SNDRV_PCM_FMTBIT_*,
> >> not of SNDRV_PCM_FORMAT_* (which are sequential integers),
> >> however some of ASoC CODEC drivers use these values instead.
> >>
> >> Found out by sparse on 0-day kernel tester.
> >>
> >> Signed-off-by: Maciej Szmigiero <mail@...iej.szmigiero.name>
> > 
> > Wow, that made me wonder how these drivers could actually work.
> 
> Maybe, by coincidence, the wrong defines contained enough bits
> set to actually select some common, working format with their
> controllers?

Well, FORMAT_S16_LE = 2, and FORMAT_S18_3LE = 40.  So bits 1, 3 and 5
are set, which corresponds to U8, S16_BE and U16_BE.  Hmm.

> > BTW, how did you detect it?  Any static analyzer like sparse or
> > smatch?  sparse didn't detect it at the last time I tried, IIRC...
> 
> I've received an e-mail from "kbuild test robot" at
> "0-DAY kernel test infrastructure" that automated testing there
> using sparse found this issue on wm9713 and stac9766 CODECs.
> 
> The exact warning was:
> >> sound/soc/codecs/stac9766.c:324:28: sparse: incorrect type in initializer (different base types)
>    sound/soc/codecs/stac9766.c:324:28:    expected unsigned long long [unsigned] [usertype] formats
>    sound/soc/codecs/stac9766.c:324:28:    got restricted snd_pcm_format_t [usertype] <noident>
> 
> What is important the warning doesn't show unless a check build
> is made with CF=-D__CHECK_ENDIAN__ .

Ah, thanks, that was the missing piece.

> Upon checking I've found the same issue also in two other CODECs,
> which aren't normally being built on x86_64 (target architecture
> for above automated build) even when SND_SOC_ALL_CODECS is selected.

Oh it'd be great if you submit fixes :)


thanks,

Takashi
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