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Thu, 9 Apr 2026 07:08:08 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id zM7JAFhQ12lhPQAAD6G6ig (envelope-from ); Thu, 09 Apr 2026 07:08:08 +0000 Date: Thu, 09 Apr 2026 09:08:07 +0200 Message-ID: <87o6jsk3vs.wl-tiwai@suse.de> From: Takashi Iwai To: Rong Zhang Cc: Jaroslav Kysela , Takashi Iwai , linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org, Icenowy Zheng Subject: Re: [PATCH 2/2] ALSA: usb-audio: Do not expose sticky volume control mixers In-Reply-To: <20260409-feaulle-rainbow-v1-2-09179e09000d@rong.moe> References: <20260409-feaulle-rainbow-v1-0-09179e09000d@rong.moe> <20260409-feaulle-rainbow-v1-2-09179e09000d@rong.moe> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/30.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-Spamd-Result: default: False [-3.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_RATELIMITED(0.00)[rspamd.com]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; RCVD_COUNT_TWO(0.00)[2]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,imap1.dmz-prg2.suse.org:helo] X-Spam-Flag: NO X-Spam-Score: -3.30 X-Spam-Level: On Wed, 08 Apr 2026 20:33:06 +0200, Rong Zhang wrote: > > Some devices expose sticky mixers that accept SET_CUR but do absolutely > nothing. Registering mixers for them confuses userspace and results in > ineffective volume control. > > Check if the volume control is sticky by setting the volume to the > maximum or minimum value, and prevent the mixer from being registered > accordingly. > > Quirky device sample: > > usb 7-1: New USB device found, idVendor=0e0b, idProduct=fa01, bcdDevice= 1.00 > usb 7-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 > usb 7-1: Product: Feaulle Rainbow > usb 7-1: Manufacturer: Generic > usb 7-1: SerialNumber: 20210726905926 > (Mic Capture Volume) > > Signed-off-by: Rong Zhang > --- > sound/usb/mixer.c | 37 +++++++++++++++++++++++++++++++++++-- > 1 file changed, 35 insertions(+), 2 deletions(-) > > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c > index a25e8145af67..9f0aed36e27d 100644 > --- a/sound/usb/mixer.c > +++ b/sound/usb/mixer.c > @@ -27,6 +27,7 @@ > * - parse available sample rates again when clock sources changed > */ > > +#include It's only for ARRAY_SIZE()? Then no need for extra inclusion. It's already included by others. > #include > #include > #include > @@ -1287,17 +1288,49 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval, > if (cval->res == 0) > cval->res = 1; > > - /* Additional checks for the proper resolution > + /* Additional checks > + * > + * Some devices expose sticky mixers that accept SET_CUR > + * but do absolutely nothing. > * > * Some devices report smaller resolutions than actually > * reacting. They don't return errors but simply clip > * to the lower aligned value. > */ > - if (cval->min + cval->res < cval->max) { > + if (cval->min < cval->max) { > + int sticky_test_values[] = { cval->min, cval->max }; > int last_valid_res = cval->res; > int saved, test, check; > + bool effective = false; > + > if (get_cur_mix_raw(cval, minchn, &saved) < 0) > goto no_res_check; > + > + for (i = 0; i < ARRAY_SIZE(sticky_test_values); i++) { > + test = sticky_test_values[i]; > + if (test == saved) > + continue; > + /* Assume non-sticky on failure. */ > + if (snd_usb_set_cur_mix_value(cval, minchn, 0, test) || > + get_cur_mix_raw(cval, minchn, &check) || > + check != saved) { /* SET_CUR effective, non-sticky. */ > + effective = true; > + break; > + } > + } > + if (!effective) { > + usb_audio_warn(cval->head.mixer->chip, > + "%d:%d: sticky mixer values (%d/%d/%d => %d), disabling\n", > + cval->head.id, mixer_ctrl_intf(cval->head.mixer), > + cval->min, cval->max, cval->res, saved); > + > + cval->initialized = 1; > + cval->min = cval->max = cval->res = 0; > + return -ENODEV; > + } > + > + if (cval->min + cval->res >= cval->max) > + goto no_res_check; Hm, it's quite lots of changes, and I'd like this to be factored out as a function instead. Maybe the resolution check code could be moved into a function, too; get_min_max_with_quirks() is too lengthy. Also, note that currently there is no error check for get_min_max*(). Your code works just because you set cval->min = cval->max, and there is an additional check at a later point of this. Ideally speaking, we should have an error check to explicitly handle a case like this. But the current code allows the error at init, at least, we tolerate the errors at reading UAC_GET_MIN and _MAX. So, if any, the error check would need to evaluate the error number and ignore -EINVAL or such... thanks, Takashi