pcm: plugin - fix avail_min calculation on rate plugin

[GitHub pull_request - opened]

alsa-project/alsa-lib pull request #218 was opened from aditpape:

commit 88e4ae27, ff1f669d introduced a dynamic recalculation of the slave's
avail_min value.
The calculated avail_min setting did not take into account, that the avail_min value
depends on the used sampling rate and must be adapted accordingly
if the slave is using a different sampling rate.
That leads to too large/too small calculated avail_min settings and inaccurate
period wake-up events if a rate converter plugin is used.

This patch is adapting the avail_min calculation to consider a different
sampling rate between actual pcm and it's slave.

Signed-off-by: Andreas Pape <apape at de.adit-jv.com>

Request URL   : https://github.com/alsa-project/alsa-lib/pull/218
Patch URL     : https://github.com/alsa-project/alsa-lib/pull/218.patch
Repository URL: https://github.com/alsa-project/alsa-lib