Re: [alsa-devel] [PATCH v2 3/5] ASoC: generic-dmaengine-pcm: Prepare formats mask for valid physical sample sizes

[Lars-Peter Clausen]

On 07/02/2014 03:47 PM, Takashi Iwai wrote:
[...]
> > +	/*
> > +	 * Prepare formats mask for valid/allowed sample types. If the dma does
> > +	 * not have support for the given physical word size, it needs to be
> > +	 * masked out so user space can not use the format which produces
> > +	 * corrupted audio.
> > +	 * In case the dma driver does not implement the slave_caps the default
> > +	 * assumption is that it supports 1, 2 and 4 bytes widths.
> > +	 */
> > +	for (i = 0; i <= SNDRV_PCM_FORMAT_LAST; i++) {
> > +		int bits = snd_pcm_format_physical_width(i);
>
> Better to add a negative value check.  Some formats return -EINVAL.

So what should we do with those formats? Not support them?

> > +
> > +		/* Enable only samples with DMA supported physical widths */
> > +		if (addr_widths & BIT(bits / 8))
>
> Just nitpicking: Using BIT() for 32bit int isn't always a wise choice
> since BIT() is defined as unsigned long.  This is a generic problem,
> though, as we see many codes using BIT() wrongly (and thus get
> compiler warnings on 64bit machines).  We should introduce a new macro
> for 32bit int...

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