Re: [PATCH v3 0/8] ALSA: usb-audio: Add quirks for linear volume devices and deconflict VID

[Takashi Iwai <tiwai@suse.de>]

On Tue, 03 Mar 2026 20:47:55 +0100,
Rong Zhang wrote:
> 
> Some quirky devices tune their volume by linearly tuning the voltage
> level (linear volume). In other words, such devices has a linear TLV
> mapping of DECLARE_TLV_DB_LINEAR(scale, TLV_DB_GAIN_MUTE, 0).
> 
> The series mainly adds quirk flags MIXER_PLAYBACK_LINEAR_VOL and
> MIXER_CAPTURE_LINEAR_VOL to represent this case respectively for
> playback and capture mixers. Afterward, apply these quirk flags on them.
> 
> Some MV-SILICON devices with these quirks also have another quirk: VID
> conflicts with Focusrite Novation (0x1235). Hence, add support for
> string-descriptor-based quirk table entries and define an entry for MV-
> SILICON to deconflict them.
> 
> Some improvements to the logic of volume range checks is also included
> in the series to help identify quirky devices with linear volume.
> 
> Changes in v3:
> - Adopt __free(kfree) on string buffers as it turns out to be able to
>   handle ERR_PTR() gracefully (thanks Takashi Iwai)
> - Improve readability by replacing the goto pattern with
>   `p->usb_string_match && p->usb_string_match->*'. The compiler should
>   generate equivalent control paths thanks to the optimizer
> - Link to v2: https://lore.kernel.org/r/20260302185900.427415-1-i@rong.moe/
> 
> Changes in v2:
> - Separate [PATCH v1 6/9] into https://lore.kernel.org/r/20260302173300.322673-1-i@rong.moe/
> - Alloc string buffers with kmalloc() instead of on stack (thanks
>   Takashi Iwai)
> - Get string descriptors in a neater way (ditto)
> - Tiny differences compared to Takashi's sugeestion:
>   - Use `IS_ERR_OR_NULL() || strcmp()' instead of `!IS_ERR_OR_NULL() &&
>     strcmp()', so failure in getting the string descriptor won't
>     resulting in quirk flags being applied to irrelevant devices
>   - Use trivial goto cleanup patterns instead of `__free(kfree)' as the
>     latter can't handle ERR_PTR()
> - Tiny differences compared to my previous reply:
>   - Use usb_string() as Takashi suggested instead of usb_cache_string(),
>     so that we can retrieve the errno and print it out on failure
> - Link to v1: https://lore.kernel.org/r/20260301213726.428505-1-i@rong.moe/
> 
> Rong Zhang (8):
>   Revert "ALSA: usb: Increase volume range that triggers a warning"
>   ALSA: usb-audio: Add helper function for volume range checks
>   ALSA: usb-audio: Improve volume range checks
>   ALSA: usb-audio: Support string-descriptor-based quirk table entry
>   ALSA: usb-audio: Deconflict VID between Focusrite Novation &
>     MV-SILICON
>   ALSA: usb-audio: Add QUIRK_FLAG_MIXER_{PLAYBACK,CAPTURE}_LINEAR_VOL
>   ALSA: usb-audio: Add linear volume quirk for Hotone Audio Pulze Mini
>   ALSA: usb-audio: Apply linear volume quirk on MV-SILICON devices

Applied all patches now to for-next branch.  Thanks.


Takashi