[alsa-devel] [PATCH 3/4] ASoC: bcm2835: Support additional samplerates up to 384kHz

Eric Anholt eric at anholt.net
Wed Nov 8 21:26:01 CET 2017


Matthias Reichl <hias at horus.com> writes:

> Sample rates are only restricted by the capabilities of the
> clock driver, so use SNDRV_PCM_RATE_CONTINUOUS instead of
> SNDRV_PCM_RATE_8000_192000.
>
> Tests (eg with pcm5122) have shown that bcm2835 works fine
> in 384kHz/32bit stereo mode, so change the maximum allowed
> rate from 192kHz to 384kHz.

The docs I've got say the maximum PCM clock freq is 25Mhz, so if my math
is right then 384kHz should be fine.  This patch is:

Reviewed-by: Eric Anholt <eric at anholt.net>

(There's a note about needing to be careful that the mash filter doesn't
give you frequencies over 25mhz, but we should be doing limits like that
in the clock driver)

I'm going to give the alsa folks a chance to look at the modes patches
first, since I know they've got strong opinions about them and I don't
at all.
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