It makes no sense to restore the saved value for a sticky mixer, since
setting any value is a no-op.

However, in some rare cases, SET_CUR is effective despite GET_CUR always
returns a constant value. These mixers are not sticky, but there's no
way to distinguish them. Without any additional information, the best
thing we can do is to set the mixer value to the maximum before bailing
out, so that a soft mixer can still reach the maximum hardware volume if
the mixer turns out to be non-sticky. Meanwhile, all channels must be
synchronized to prevent imbalance volume.

Fixes: 86aa1ea1f15c ("ALSA: usb-audio: Do not expose sticky mixers")
Signed-off-by: Rong Zhang <i@rong.moe>
---
 sound/usb/mixer.c | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 5fba456eb4a9..fb37bb8ad9a9 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1371,10 +1371,8 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
 				goto no_checks;
 
 			ret = check_sticky_volume_control(cval, minchn, saved);
-			if (ret < 0) {
-				snd_usb_set_cur_mix_value(cval, minchn, 0, saved);
-				return ret;
-			}
+			if (ret < 0)
+				goto sticky;
 
 			if (cval->min + cval->res < cval->max)
 				check_volume_control_res(cval, minchn, saved);
@@ -1431,6 +1429,33 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
 	}
 
 	return 0;
+
+sticky:
+	/*
+	 * It makes no sense to restore the saved value for a sticky mixer,
+	 * since setting any value is a no-op.
+	 *
+	 * However, in some rare cases, SET_CUR is effective despite GET_CUR
+	 * always returns a constant value. These mixers are not sticky, but
+	 * there's no way to distinguish them. Without any additional
+	 * information, the best thing we can do is to set the mixer value to
+	 * the maximum before bailing out, so that a soft mixer can still reach
+	 * the maximum hardware volume if the mixer turns out to be non-sticky.
+	 * Meanwhile, all channels must be synchronized to prevent imbalance
+	 * volume.
+	 */
+	if (!cval->cmask) {
+		snd_usb_set_cur_mix_value(cval, 0, 0, cval->max);
+	} else {
+		for (i = 0; i < MAX_CHANNELS; i++) {
+			idx = 0;
+			if (cval->cmask & BIT(i)) {
+				snd_usb_set_cur_mix_value(cval, i + 1, idx, cval->max);
+				idx++;
+			}
+		}
+	}
+	return ret;
 }
 
 #define get_min_max(cval, def)	get_min_max_with_quirks(cval, def, NULL)

---
base-commit: 2c142b63c8ee982cdfdba49a616027c266294838
change-id: 2ae46b0d-uac-sticky-error-path-496e4f0caa0f

Thanks,
Rong

On Sat, 30 May 2026 21:52:49 +0200,
Rong Zhang wrote:
> 
> It makes no sense to restore the saved value for a sticky mixer, since
> setting any value is a no-op.
> 
> However, in some rare cases, SET_CUR is effective despite GET_CUR always
> returns a constant value. These mixers are not sticky, but there's no
> way to distinguish them. Without any additional information, the best
> thing we can do is to set the mixer value to the maximum before bailing
> out, so that a soft mixer can still reach the maximum hardware volume if
> the mixer turns out to be non-sticky. Meanwhile, all channels must be
> synchronized to prevent imbalance volume.
> 
> Fixes: 86aa1ea1f15c ("ALSA: usb-audio: Do not expose sticky mixers")
> Signed-off-by: Rong Zhang <i@rong.moe>
> ---
>  sound/usb/mixer.c | 33 +++++++++++++++++++++++++++++----
>  1 file changed, 29 insertions(+), 4 deletions(-)
> 
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 5fba456eb4a9..fb37bb8ad9a9 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -1371,10 +1371,8 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
>  				goto no_checks;
>  
>  			ret = check_sticky_volume_control(cval, minchn, saved);
> -			if (ret < 0) {
> -				snd_usb_set_cur_mix_value(cval, minchn, 0, saved);
> -				return ret;
> -			}
> +			if (ret < 0)
> +				goto sticky;
>  
>  			if (cval->min + cval->res < cval->max)
>  				check_volume_control_res(cval, minchn, saved);
> @@ -1431,6 +1429,33 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
>  	}
>  
>  	return 0;
> +
> +sticky:
> +	/*
> +	 * It makes no sense to restore the saved value for a sticky mixer,
> +	 * since setting any value is a no-op.
> +	 *
> +	 * However, in some rare cases, SET_CUR is effective despite GET_CUR
> +	 * always returns a constant value. These mixers are not sticky, but
> +	 * there's no way to distinguish them. Without any additional
> +	 * information, the best thing we can do is to set the mixer value to
> +	 * the maximum before bailing out, so that a soft mixer can still reach
> +	 * the maximum hardware volume if the mixer turns out to be non-sticky.
> +	 * Meanwhile, all channels must be synchronized to prevent imbalance
> +	 * volume.
> +	 */
> +	if (!cval->cmask) {
> +		snd_usb_set_cur_mix_value(cval, 0, 0, cval->max);
> +	} else {
> +		for (i = 0; i < MAX_CHANNELS; i++) {
> +			idx = 0;
> +			if (cval->cmask & BIT(i)) {
> +				snd_usb_set_cur_mix_value(cval, i + 1, idx, cval->max);
> +				idx++;
> +			}
> +		}
> +	}
> +	return ret;

This change is supposed to be applied only to 7.1, and 7.2 should take
another your series ("ALSA: usb-audio: MIXER_GET_CUR_BROKEN related
changes for 7.2") instead, right?  If so, at merging the latter, I'll
revert this one as a preliminary.


thanks,

Takashi

Hi Takashi,

On Sun, 2026-05-31 at 15:23 +0200, Takashi Iwai wrote:
> On Sat, 30 May 2026 21:52:49 +0200,
> Rong Zhang wrote:
> > 
> > It makes no sense to restore the saved value for a sticky mixer, since
> > setting any value is a no-op.
> > 
> > However, in some rare cases, SET_CUR is effective despite GET_CUR always
> > returns a constant value. These mixers are not sticky, but there's no
> > way to distinguish them. Without any additional information, the best
> > thing we can do is to set the mixer value to the maximum before bailing
> > out, so that a soft mixer can still reach the maximum hardware volume if
> > the mixer turns out to be non-sticky. Meanwhile, all channels must be
> > synchronized to prevent imbalance volume.
> > 
> > Fixes: 86aa1ea1f15c ("ALSA: usb-audio: Do not expose sticky mixers")
> > Signed-off-by: Rong Zhang <i@rong.moe>
> > ---
> >  sound/usb/mixer.c | 33 +++++++++++++++++++++++++++++----
> >  1 file changed, 29 insertions(+), 4 deletions(-)
> > 
> > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> > index 5fba456eb4a9..fb37bb8ad9a9 100644
> > --- a/sound/usb/mixer.c
> > +++ b/sound/usb/mixer.c
> > @@ -1371,10 +1371,8 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
> >  				goto no_checks;
> >  
> >  			ret = check_sticky_volume_control(cval, minchn, saved);
> > -			if (ret < 0) {
> > -				snd_usb_set_cur_mix_value(cval, minchn, 0, saved);
> > -				return ret;
> > -			}
> > +			if (ret < 0)
> > +				goto sticky;
> >  
> >  			if (cval->min + cval->res < cval->max)
> >  				check_volume_control_res(cval, minchn, saved);
> > @@ -1431,6 +1429,33 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
> >  	}
> >  
> >  	return 0;
> > +
> > +sticky:
> > +	/*
> > +	 * It makes no sense to restore the saved value for a sticky mixer,
> > +	 * since setting any value is a no-op.
> > +	 *
> > +	 * However, in some rare cases, SET_CUR is effective despite GET_CUR
> > +	 * always returns a constant value. These mixers are not sticky, but
> > +	 * there's no way to distinguish them. Without any additional
> > +	 * information, the best thing we can do is to set the mixer value to
> > +	 * the maximum before bailing out, so that a soft mixer can still reach
> > +	 * the maximum hardware volume if the mixer turns out to be non-sticky.
> > +	 * Meanwhile, all channels must be synchronized to prevent imbalance
> > +	 * volume.
> > +	 */
> > +	if (!cval->cmask) {
> > +		snd_usb_set_cur_mix_value(cval, 0, 0, cval->max);
> > +	} else {
> > +		for (i = 0; i < MAX_CHANNELS; i++) {
> > +			idx = 0;
> > +			if (cval->cmask & BIT(i)) {
> > +				snd_usb_set_cur_mix_value(cval, i + 1, idx, cval->max);
> > +				idx++;
> > +			}
> > +		}
> > +	}
> > +	return ret;
> 
> This change is supposed to be applied only to 7.1, 
> 

This patch is meant for both 7.1 and 7.2.

> and 7.2 should take
> another your series ("ALSA: usb-audio: MIXER_GET_CUR_BROKEN related
> changes for 7.2") instead, right?
> 

Right.

>   If so, at merging the latter, I'll
> revert this one as a preliminary.

Please don't revert this one in 7.2.

It is needed to make any future devices like that to at least have
audible volume out-of-box. Without it, users will have to wait for an
quirk table entry for their devices (or add one themselves). Since
setting the mixer value to maximum should be safe on both categories of
devices (sticky, effective SET_CUR but broken GET_CUR), I'd prefer to
retain this patch in 7.2 too.

Another reason of retaining it is that the current error path only
"restores" the garbage GET_CUR value for minchn, so it could lead to
imbalance volume if the mixer has multiple channels. In the effective
SET_CUR but broken GET_CUR case, we would still have to fix the error
path anyway to synchronize all channels. Since this patch does the job
and synchronize all channels using a non-garbage value, it should be
fine to retain it in 7.2.

That being said, this patch has a trivial single-line conflict in 7.2
because my series adding QUIRK_FLAG_MIXER_GET_CUR_BROKEN narrowed the
sticky path down to `ret == -ENODEV'. I can resubmit the series for 7.2
to include a rebased version of this patch, should you prefer.

Thanks,
Rong

> 
> 
> thanks,
> 
> Takashi

On Sun, 31 May 2026 15:55:46 +0200,
Rong Zhang wrote:
>> 
> Hi Takashi,
> 
> On Sun, 2026-05-31 at 15:23 +0200, Takashi Iwai wrote:
> > On Sat, 30 May 2026 21:52:49 +0200,
> > Rong Zhang wrote:
> > > 
> > > It makes no sense to restore the saved value for a sticky mixer, since
> > > setting any value is a no-op.
> > > 
> > > However, in some rare cases, SET_CUR is effective despite GET_CUR always
> > > returns a constant value. These mixers are not sticky, but there's no
> > > way to distinguish them. Without any additional information, the best
> > > thing we can do is to set the mixer value to the maximum before bailing
> > > out, so that a soft mixer can still reach the maximum hardware volume if
> > > the mixer turns out to be non-sticky. Meanwhile, all channels must be
> > > synchronized to prevent imbalance volume.
> > > 
> > > Fixes: 86aa1ea1f15c ("ALSA: usb-audio: Do not expose sticky mixers")
> > > Signed-off-by: Rong Zhang <i@rong.moe>
> > > ---
> > >  sound/usb/mixer.c | 33 +++++++++++++++++++++++++++++----
> > >  1 file changed, 29 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> > > index 5fba456eb4a9..fb37bb8ad9a9 100644
> > > --- a/sound/usb/mixer.c
> > > +++ b/sound/usb/mixer.c
> > > @@ -1371,10 +1371,8 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
> > >  				goto no_checks;
> > >  
> > >  			ret = check_sticky_volume_control(cval, minchn, saved);
> > > -			if (ret < 0) {
> > > -				snd_usb_set_cur_mix_value(cval, minchn, 0, saved);
> > > -				return ret;
> > > -			}
> > > +			if (ret < 0)
> > > +				goto sticky;
> > >  
> > >  			if (cval->min + cval->res < cval->max)
> > >  				check_volume_control_res(cval, minchn, saved);
> > > @@ -1431,6 +1429,33 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
> > >  	}
> > >  
> > >  	return 0;
> > > +
> > > +sticky:
> > > +	/*
> > > +	 * It makes no sense to restore the saved value for a sticky mixer,
> > > +	 * since setting any value is a no-op.
> > > +	 *
> > > +	 * However, in some rare cases, SET_CUR is effective despite GET_CUR
> > > +	 * always returns a constant value. These mixers are not sticky, but
> > > +	 * there's no way to distinguish them. Without any additional
> > > +	 * information, the best thing we can do is to set the mixer value to
> > > +	 * the maximum before bailing out, so that a soft mixer can still reach
> > > +	 * the maximum hardware volume if the mixer turns out to be non-sticky.
> > > +	 * Meanwhile, all channels must be synchronized to prevent imbalance
> > > +	 * volume.
> > > +	 */
> > > +	if (!cval->cmask) {
> > > +		snd_usb_set_cur_mix_value(cval, 0, 0, cval->max);
> > > +	} else {
> > > +		for (i = 0; i < MAX_CHANNELS; i++) {
> > > +			idx = 0;
> > > +			if (cval->cmask & BIT(i)) {
> > > +				snd_usb_set_cur_mix_value(cval, i + 1, idx, cval->max);
> > > +				idx++;
> > > +			}
> > > +		}
> > > +	}
> > > +	return ret;
> > 
> > This change is supposed to be applied only to 7.1, 
> > 
> 
> This patch is meant for both 7.1 and 7.2.
> 
> > and 7.2 should take
> > another your series ("ALSA: usb-audio: MIXER_GET_CUR_BROKEN related
> > changes for 7.2") instead, right?
> > 
> 
> Right.
> 
> >   If so, at merging the latter, I'll
> > revert this one as a preliminary.
> 
> Please don't revert this one in 7.2.
> 
> It is needed to make any future devices like that to at least have
> audible volume out-of-box. Without it, users will have to wait for an
> quirk table entry for their devices (or add one themselves). Since
> setting the mixer value to maximum should be safe on both categories of
> devices (sticky, effective SET_CUR but broken GET_CUR), I'd prefer to
> retain this patch in 7.2 too.
> 
> Another reason of retaining it is that the current error path only
> "restores" the garbage GET_CUR value for minchn, so it could lead to
> imbalance volume if the mixer has multiple channels. In the effective
> SET_CUR but broken GET_CUR case, we would still have to fix the error
> path anyway to synchronize all channels. Since this patch does the job
> and synchronize all channels using a non-garbage value, it should be
> fine to retain it in 7.2.
> 
> That being said, this patch has a trivial single-line conflict in 7.2
> because my series adding QUIRK_FLAG_MIXER_GET_CUR_BROKEN narrowed the
> sticky path down to `ret == -ENODEV'. I can resubmit the series for 7.2
> to include a rebased version of this patch, should you prefer.

OK, then let me merge this one to for-linus, and merge to for-next
branch at first.  Then resubmit the patches that can be applied
cleanly on for-next branch.  I can merge and resolve conflicts
locally, but this would become a problem when backporting to older
stable kernels in future.


thanks,

Takashi

Hi Takashi,

On Sun, 2026-05-31 at 16:07 +0200, Takashi Iwai wrote:
> On Sun, 31 May 2026 15:55:46 +0200,
> Rong Zhang wrote:
> > > 
> > Hi Takashi,
> > 
> > On Sun, 2026-05-31 at 15:23 +0200, Takashi Iwai wrote:
> > > On Sat, 30 May 2026 21:52:49 +0200,
> > > Rong Zhang wrote:
> > > > 
> > > > It makes no sense to restore the saved value for a sticky mixer, since
> > > > setting any value is a no-op.
> > > > 
> > > > However, in some rare cases, SET_CUR is effective despite GET_CUR always
> > > > returns a constant value. These mixers are not sticky, but there's no
> > > > way to distinguish them. Without any additional information, the best
> > > > thing we can do is to set the mixer value to the maximum before bailing
> > > > out, so that a soft mixer can still reach the maximum hardware volume if
> > > > the mixer turns out to be non-sticky. Meanwhile, all channels must be
> > > > synchronized to prevent imbalance volume.
> > > > 
> > > > Fixes: 86aa1ea1f15c ("ALSA: usb-audio: Do not expose sticky mixers")
> > > > Signed-off-by: Rong Zhang <i@rong.moe>
> > > > ---
> > > >  sound/usb/mixer.c | 33 +++++++++++++++++++++++++++++----
> > > >  1 file changed, 29 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> > > > index 5fba456eb4a9..fb37bb8ad9a9 100644
> > > > --- a/sound/usb/mixer.c
> > > > +++ b/sound/usb/mixer.c
> > > > @@ -1371,10 +1371,8 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
> > > >  				goto no_checks;
> > > >  
> > > >  			ret = check_sticky_volume_control(cval, minchn, saved);
> > > > -			if (ret < 0) {
> > > > -				snd_usb_set_cur_mix_value(cval, minchn, 0, saved);
> > > > -				return ret;
> > > > -			}
> > > > +			if (ret < 0)
> > > > +				goto sticky;
> > > >  
> > > >  			if (cval->min + cval->res < cval->max)
> > > >  				check_volume_control_res(cval, minchn, saved);
> > > > @@ -1431,6 +1429,33 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
> > > >  	}
> > > >  
> > > >  	return 0;
> > > > +
> > > > +sticky:
> > > > +	/*
> > > > +	 * It makes no sense to restore the saved value for a sticky mixer,
> > > > +	 * since setting any value is a no-op.
> > > > +	 *
> > > > +	 * However, in some rare cases, SET_CUR is effective despite GET_CUR
> > > > +	 * always returns a constant value. These mixers are not sticky, but
> > > > +	 * there's no way to distinguish them. Without any additional
> > > > +	 * information, the best thing we can do is to set the mixer value to
> > > > +	 * the maximum before bailing out, so that a soft mixer can still reach
> > > > +	 * the maximum hardware volume if the mixer turns out to be non-sticky.
> > > > +	 * Meanwhile, all channels must be synchronized to prevent imbalance
> > > > +	 * volume.
> > > > +	 */
> > > > +	if (!cval->cmask) {
> > > > +		snd_usb_set_cur_mix_value(cval, 0, 0, cval->max);
> > > > +	} else {
> > > > +		for (i = 0; i < MAX_CHANNELS; i++) {
> > > > +			idx = 0;
> > > > +			if (cval->cmask & BIT(i)) {
> > > > +				snd_usb_set_cur_mix_value(cval, i + 1, idx, cval->max);
> > > > +				idx++;
> > > > +			}
> > > > +		}
> > > > +	}
> > > > +	return ret;
> > > 
> > > This change is supposed to be applied only to 7.1, 
> > > 
> > 
> > This patch is meant for both 7.1 and 7.2.
> > 
> > > and 7.2 should take
> > > another your series ("ALSA: usb-audio: MIXER_GET_CUR_BROKEN related
> > > changes for 7.2") instead, right?
> > > 
> > 
> > Right.
> > 
> > >   If so, at merging the latter, I'll
> > > revert this one as a preliminary.
> > 
> > Please don't revert this one in 7.2.
> > 
> > It is needed to make any future devices like that to at least have
> > audible volume out-of-box. Without it, users will have to wait for an
> > quirk table entry for their devices (or add one themselves). Since
> > setting the mixer value to maximum should be safe on both categories of
> > devices (sticky, effective SET_CUR but broken GET_CUR), I'd prefer to
> > retain this patch in 7.2 too.
> > 
> > Another reason of retaining it is that the current error path only
> > "restores" the garbage GET_CUR value for minchn, so it could lead to
> > imbalance volume if the mixer has multiple channels. In the effective
> > SET_CUR but broken GET_CUR case, we would still have to fix the error
> > path anyway to synchronize all channels. Since this patch does the job
> > and synchronize all channels using a non-garbage value, it should be
> > fine to retain it in 7.2.
> > 
> > That being said, this patch has a trivial single-line conflict in 7.2
> > because my series adding QUIRK_FLAG_MIXER_GET_CUR_BROKEN narrowed the
> > sticky path down to `ret == -ENODEV'. I can resubmit the series for 7.2
> > to include a rebased version of this patch, should you prefer.
> 
> OK, then let me merge this one to for-linus, and merge to for-next
> branch at first.  
> 

Many thanks.

> Then resubmit the patches that can be applied
> cleanly on for-next branch.  I can merge and resolve conflicts
> locally, but this would become a problem when backporting to older
> stable kernels in future.

Oh, I just noticed that you haven't pushed anything to your for-next
branch after merging my QUIRK_FLAG_MIXER_GET_CUR_BROKEN series, so the
ship hasn't sailed yet. Did you mean that you will drop my "ALSA: usb-
audio: Add QUIRK_FLAG_MIXER_GET_CUR_BROKEN for Sennheiser MOMENTUM 3"
from your local branch so that I can rebase and resubmit the series
then?

It sounds good to me. In this way I can also integrate the "ALSA: usb-
audio: MIXER_GET_CUR_BROKEN related changes for 7.2" series into the
QUIRK_FLAG_MIXER_GET_CUR_BROKEN series so things get tidier.

Thanks,
Rong

> 
> 
> thanks,
> 
> Takashi

On Sun, 31 May 2026 16:19:42 +0200,
Rong Zhang wrote:
> 
> Hi Takashi,
> 
> On Sun, 2026-05-31 at 16:07 +0200, Takashi Iwai wrote:
> > On Sun, 31 May 2026 15:55:46 +0200,
> > Rong Zhang wrote:
> > > > 
> > > Hi Takashi,
> > > 
> > > On Sun, 2026-05-31 at 15:23 +0200, Takashi Iwai wrote:
> > > > On Sat, 30 May 2026 21:52:49 +0200,
> > > > Rong Zhang wrote:
> > > > > 
> > > > > It makes no sense to restore the saved value for a sticky mixer, since
> > > > > setting any value is a no-op.
> > > > > 
> > > > > However, in some rare cases, SET_CUR is effective despite GET_CUR always
> > > > > returns a constant value. These mixers are not sticky, but there's no
> > > > > way to distinguish them. Without any additional information, the best
> > > > > thing we can do is to set the mixer value to the maximum before bailing
> > > > > out, so that a soft mixer can still reach the maximum hardware volume if
> > > > > the mixer turns out to be non-sticky. Meanwhile, all channels must be
> > > > > synchronized to prevent imbalance volume.
> > > > > 
> > > > > Fixes: 86aa1ea1f15c ("ALSA: usb-audio: Do not expose sticky mixers")
> > > > > Signed-off-by: Rong Zhang <i@rong.moe>
> > > > > ---
> > > > >  sound/usb/mixer.c | 33 +++++++++++++++++++++++++++++----
> > > > >  1 file changed, 29 insertions(+), 4 deletions(-)
> > > > > 
> > > > > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> > > > > index 5fba456eb4a9..fb37bb8ad9a9 100644
> > > > > --- a/sound/usb/mixer.c
> > > > > +++ b/sound/usb/mixer.c
> > > > > @@ -1371,10 +1371,8 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
> > > > >  				goto no_checks;
> > > > >  
> > > > >  			ret = check_sticky_volume_control(cval, minchn, saved);
> > > > > -			if (ret < 0) {
> > > > > -				snd_usb_set_cur_mix_value(cval, minchn, 0, saved);
> > > > > -				return ret;
> > > > > -			}
> > > > > +			if (ret < 0)
> > > > > +				goto sticky;
> > > > >  
> > > > >  			if (cval->min + cval->res < cval->max)
> > > > >  				check_volume_control_res(cval, minchn, saved);
> > > > > @@ -1431,6 +1429,33 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
> > > > >  	}
> > > > >  
> > > > >  	return 0;
> > > > > +
> > > > > +sticky:
> > > > > +	/*
> > > > > +	 * It makes no sense to restore the saved value for a sticky mixer,
> > > > > +	 * since setting any value is a no-op.
> > > > > +	 *
> > > > > +	 * However, in some rare cases, SET_CUR is effective despite GET_CUR
> > > > > +	 * always returns a constant value. These mixers are not sticky, but
> > > > > +	 * there's no way to distinguish them. Without any additional
> > > > > +	 * information, the best thing we can do is to set the mixer value to
> > > > > +	 * the maximum before bailing out, so that a soft mixer can still reach
> > > > > +	 * the maximum hardware volume if the mixer turns out to be non-sticky.
> > > > > +	 * Meanwhile, all channels must be synchronized to prevent imbalance
> > > > > +	 * volume.
> > > > > +	 */
> > > > > +	if (!cval->cmask) {
> > > > > +		snd_usb_set_cur_mix_value(cval, 0, 0, cval->max);
> > > > > +	} else {
> > > > > +		for (i = 0; i < MAX_CHANNELS; i++) {
> > > > > +			idx = 0;
> > > > > +			if (cval->cmask & BIT(i)) {
> > > > > +				snd_usb_set_cur_mix_value(cval, i + 1, idx, cval->max);
> > > > > +				idx++;
> > > > > +			}
> > > > > +		}
> > > > > +	}
> > > > > +	return ret;
> > > > 
> > > > This change is supposed to be applied only to 7.1, 
> > > > 
> > > 
> > > This patch is meant for both 7.1 and 7.2.
> > > 
> > > > and 7.2 should take
> > > > another your series ("ALSA: usb-audio: MIXER_GET_CUR_BROKEN related
> > > > changes for 7.2") instead, right?
> > > > 
> > > 
> > > Right.
> > > 
> > > >   If so, at merging the latter, I'll
> > > > revert this one as a preliminary.
> > > 
> > > Please don't revert this one in 7.2.
> > > 
> > > It is needed to make any future devices like that to at least have
> > > audible volume out-of-box. Without it, users will have to wait for an
> > > quirk table entry for their devices (or add one themselves). Since
> > > setting the mixer value to maximum should be safe on both categories of
> > > devices (sticky, effective SET_CUR but broken GET_CUR), I'd prefer to
> > > retain this patch in 7.2 too.
> > > 
> > > Another reason of retaining it is that the current error path only
> > > "restores" the garbage GET_CUR value for minchn, so it could lead to
> > > imbalance volume if the mixer has multiple channels. In the effective
> > > SET_CUR but broken GET_CUR case, we would still have to fix the error
> > > path anyway to synchronize all channels. Since this patch does the job
> > > and synchronize all channels using a non-garbage value, it should be
> > > fine to retain it in 7.2.
> > > 
> > > That being said, this patch has a trivial single-line conflict in 7.2
> > > because my series adding QUIRK_FLAG_MIXER_GET_CUR_BROKEN narrowed the
> > > sticky path down to `ret == -ENODEV'. I can resubmit the series for 7.2
> > > to include a rebased version of this patch, should you prefer.
> > 
> > OK, then let me merge this one to for-linus, and merge to for-next
> > branch at first.  
> > 
> 
> Many thanks.
> 
> > Then resubmit the patches that can be applied
> > cleanly on for-next branch.  I can merge and resolve conflicts
> > locally, but this would become a problem when backporting to older
> > stable kernels in future.
> 
> Oh, I just noticed that you haven't pushed anything to your for-next
> branch after merging my QUIRK_FLAG_MIXER_GET_CUR_BROKEN series, so the
> ship hasn't sailed yet. Did you mean that you will drop my "ALSA: usb-
> audio: Add QUIRK_FLAG_MIXER_GET_CUR_BROKEN for Sennheiser MOMENTUM 3"
> from your local branch so that I can rebase and resubmit the series
> then?
> 
> It sounds good to me. In this way I can also integrate the "ALSA: usb-
> audio: MIXER_GET_CUR_BROKEN related changes for 7.2" series into the
> QUIRK_FLAG_MIXER_GET_CUR_BROKEN series so things get tidier.

Yeah, I temporarily merged your series but dropped again.
Now I took "ALSA: usb-audio: Set the value of potential sticky mixers
to maximum" to for-linus branch, and for-next is synced with it.

So feel free to work on for-next branch and resubmit the patches to be
applied there.


thanks,

Takashi

Hi Rong,

I can confirm this works:

* Kernel logs `usb 1-3.2: 9:1: sticky mixer values (-32768/-32513/1 =>
-32577), disabling`
* Volume behaves as expected.

Thanks everyone for looking into this.

Thanks,
Steve

On Sun, 31 May 2026 at 05:53, Rong Zhang <i@rong.moe> wrote:
>
> It makes no sense to restore the saved value for a sticky mixer, since
> setting any value is a no-op.
>
> However, in some rare cases, SET_CUR is effective despite GET_CUR always
> returns a constant value. These mixers are not sticky, but there's no
> way to distinguish them. Without any additional information, the best
> thing we can do is to set the mixer value to the maximum before bailing
> out, so that a soft mixer can still reach the maximum hardware volume if
> the mixer turns out to be non-sticky. Meanwhile, all channels must be
> synchronized to prevent imbalance volume.
>
> Fixes: 86aa1ea1f15c ("ALSA: usb-audio: Do not expose sticky mixers")
> Signed-off-by: Rong Zhang <i@rong.moe>
> ---
>  sound/usb/mixer.c | 33 +++++++++++++++++++++++++++++----
>  1 file changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 5fba456eb4a9..fb37bb8ad9a9 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -1371,10 +1371,8 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
>                                 goto no_checks;
>
>                         ret = check_sticky_volume_control(cval, minchn, saved);
> -                       if (ret < 0) {
> -                               snd_usb_set_cur_mix_value(cval, minchn, 0, saved);
> -                               return ret;
> -                       }
> +                       if (ret < 0)
> +                               goto sticky;
>
>                         if (cval->min + cval->res < cval->max)
>                                 check_volume_control_res(cval, minchn, saved);
> @@ -1431,6 +1429,33 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
>         }
>
>         return 0;
> +
> +sticky:
> +       /*
> +        * It makes no sense to restore the saved value for a sticky mixer,
> +        * since setting any value is a no-op.
> +        *
> +        * However, in some rare cases, SET_CUR is effective despite GET_CUR
> +        * always returns a constant value. These mixers are not sticky, but
> +        * there's no way to distinguish them. Without any additional
> +        * information, the best thing we can do is to set the mixer value to
> +        * the maximum before bailing out, so that a soft mixer can still reach
> +        * the maximum hardware volume if the mixer turns out to be non-sticky.
> +        * Meanwhile, all channels must be synchronized to prevent imbalance
> +        * volume.
> +        */
> +       if (!cval->cmask) {
> +               snd_usb_set_cur_mix_value(cval, 0, 0, cval->max);
> +       } else {
> +               for (i = 0; i < MAX_CHANNELS; i++) {
> +                       idx = 0;
> +                       if (cval->cmask & BIT(i)) {
> +                               snd_usb_set_cur_mix_value(cval, i + 1, idx, cval->max);
> +                               idx++;
> +                       }
> +               }
> +       }
> +       return ret;
>  }
>
>  #define get_min_max(cval, def) get_min_max_with_quirks(cval, def, NULL)
>
> ---
> base-commit: 2c142b63c8ee982cdfdba49a616027c266294838
> change-id: 2ae46b0d-uac-sticky-error-path-496e4f0caa0f
>
> Thanks,
> Rong
>