Re: [PATCH] ALSA: hda: Fix cached processing coefficient verbs

[Takashi Iwai]

On Tue, 07 Jul 2026 15:24:19 +0200,
raoxu wrote:
> 
> From: Xu Rao <raoxu@xxxxxxxxxxxxx>
> 
> Intel HD Audio defines Coefficient Index and Processing Coefficient as
> separate audio widget controls in the Audio Widget Verb Definitions:
> Coefficient Index selects the coefficient slot, while Processing
> Coefficient accesses the value at the selected slot.
> 
> hda_reg_read_coef() selects the slot with AC_VERB_SET_COEF_INDEX, but
> then uses AC_VERB_GET_COEF_INDEX for the value read.  That reads back the
> selected index instead of the coefficient value.  hda_reg_write_coef()
> has the same issue and builds the value write from AC_VERB_GET_COEF_INDEX
> instead of AC_VERB_SET_PROC_COEF.
> 
> This only affects the regmap coefficient cache path used by codecs that
> set codec->cache_coef.  Direct coefficient helpers already use the normal
> SET_COEF_INDEX followed by GET_PROC_COEF or SET_PROC_COEF sequence, which
> is likely why this has not been noticed widely.
> 
> Use AC_VERB_GET_PROC_COEF for cached coefficient reads and
> AC_VERB_SET_PROC_COEF for cached coefficient writes.
> 
> Fixes: 40ba66a702b8 ("ALSA: hda - Add cache support for COEF read/write")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Xu Rao <raoxu@xxxxxxxxxxxxx>

Ouch, this is a brown-paper-bag bug.
Applied now.  Thanks!


Takashi