Re: [PATCH v25 14/16] docs: describe virtio-sound capture options

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] docs: sound: virtio-snd module parameters omitted in
  alsa-configuration.rst
--

commit fc63ed4859aff78c0a8bfa3a6ac071eee34558c9
Author: Joonho Lee <mynameisjune111@gmail.com>

docs: describe virtio-sound capture options

This commit documents virtio-snd capture buffer handling in
Documentation/sound/alsa-configuration.rst and adds entries for the
virtio_snd.capture_packed_status and virtio_snd.capture_pause_restart
parameters in Documentation/admin-guide/kernel-parameters.txt.

> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index e75344f4e0cde..ca3fd768b4395 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -8344,6 +8344,20 @@ Kernel parameters
>  
>  			Can be used multiple times for multiple devices.
>  
> +	virtio_snd.capture_packed_status= [HW,ALSA]
> +			Read an explicitly enabled packed status trailer after
> +			the returned capture data. The fixed status scatterlist is
> +			used by default.
> +			Format: <bool>
> +			Default: false.
> +
> +	virtio_snd.capture_pause_restart= [HW,ALSA]
> +			Stop and release the stream when pausing capture. On
> +			resume, send PREPARE and START. If disabled, pause uses
> +			STOP and START while retaining the prepared stream.
> +			Format: <bool>
> +			Default: false.
> +
>  	vga=		[BOOT,X86-32] Select a particular video mode
>  			See Documentation/arch/x86/boot.rst and
>  			Documentation/admin-guide/svga.rst.
> diff --git a/Documentation/sound/alsa-configuration.rst b/Documentation/sound/alsa-configuration.rst
> index 689eccf6a5921..d40c683abc63e 100644
> --- a/Documentation/sound/alsa-configuration.rst
> +++ b/Documentation/sound/alsa-configuration.rst
> @@ -2537,6 +2537,21 @@ midi_devs
>  
>  This module supports multiple cards.
>  
> +Module virtio-snd
> +-----------------
> +
> +Virtio-sound capture receives data into a separate request buffer for each
> +PCM period. The driver validates the responses and appends frame-aligned audio
> +to the ALSA ring in request order. Valid short responses are retained. Empty
> +responses are accepted only during bounded startup or for requests already in
> +flight at STOP or PAUSE.
> +
> +On MMU systems, the request buffers are vmalloc-backed and page-rounded
> +individually. Allocator rounding can make total additional memory exceed the
> +ALSA ring size, especially with small periods. The request buffers remain
> +allocated from hw_params until hw_free.
> +Captured audio is copied from each request buffer into the ALSA ring.

[Severity: Low]
Should capture_packed_status and capture_pause_restart also be documented
here under the "Module virtio-snd" section?

CONFIG_SND_VIRTIO is tristate and defines these options with
module_param_named() in sound/virtio/virtio_pcm_ops.c, while
Documentation/admin-guide/kernel-parameters.txt directs [HW,ALSA] users
to Documentation/sound/alsa-configuration.rst for per-driver ALSA module
parameters.  This new "Module virtio-snd" subsection sits inside the
"Module parameters" section of alsa-configuration.rst, so readers looking
there for the module's parameters will not find capture_packed_status or
capture_pause_restart listed.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261111025655.63951-1-mynameisjune111@gmail.com?part=14