Re: [PATCH v18 03/12] ALSA: pcm: add an optional reset operation under the stream lock

[sashiko-bot@kernel.org]

> A driver may need to synchronize private capture accounting with the
> common RESET pointer observation and the core's position rebase.
> 
> Add an optional reset operation called under the member's stream lock.
> Expose snd_pcm_lib_reset() so the callback can retain common pointer and
> time handling. On zero return the core completes that member's rebase
> before unlocking it. Drivers without the callback retain the ioctl path.
> The operation is also used after a successful prepare.
> 
> Zero permits the position rebase; it does not promise XRUN recovery. A
> negative return skips the core rebase, so a callback returning an error
> must leave coherent pointer state even after partial work.
> 
> Linked RESET and prepare stop at the first error without rollback.
> Earlier callback members may already have completed. Legacy members keep
> the existing post_action policy. Applications must recover the group
> after partial failure before relying on shared positions.
> 
> This adds an internal kernel operation and no userspace ioctl or layout.
> Out-of-tree modules using snd_pcm_ops need to be rebuilt.
> 
> Complete appl_ptr rebasing once in the callback path. A later linked
> member can sleep in prepare while the earlier member accepts SYNC_PTR; a
> subsequent unlocked post_prepare assignment would overwrite that
> acknowledgment. Keep explicit RESET playback silence processing and
> leave prepare-time filling to the normal START path, preserving samples
> written and rewound after prepare.
> Signed-off-by: Joonho Lee <mynameisjune111@gmail.com>

Sashiko has reviewed this patch and found no issues.

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