Message-ID: <YAwDkhRVkrEna8pV@audible.transient.net>
Date:   Sat, 23 Jan 2021 11:08:02 +0000
From:   Jamie Heilman <jamie@...ible.transient.net>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: bisected regression in v5.11-rc1 snd-usb-audio

Takashi Iwai wrote:
> On Fri, 22 Jan 2021 11:03:48 +0100,
> Jamie Heilman wrote:
> > 
> > Takashi Iwai wrote:
> > > You seem hitting a firmware bug, and it doesn't look like the only
> > > case.  Interestingly, the backport of 5.11 USB-audio stuff on 5.3
> > > kernel on openSUSE Leap 15.2 caused a similar bug on Steinberg device,
> > > while it worked with 5.11-rc.  So I thought this specific with the
> > > older kernel (in USB core changes or such), but my guess seems wrong,
> > > and the bug looks remaining in 5.11 for some cases.
> > > 
> > > Below is the fix patch.  Please give it a try.
> > > 
> > > 
> > > thanks,
> > > 
> > > Takashi
> > > 
> > > -- 8< --
> > > From: Takashi Iwai <tiwai@...e.de>
> > > Subject: [PATCH] ALSA: usb-audio: workaround for iface reset issue
> > > 
> > > The recently introduced sample rate validation code seems causing a
> > > problem on some devices; namely, after performing this, the bus gets
> > > screwed and it influences even on other USB devices.
> > > As a quick workaround, perform it only for the necessary devices;
> > > currently MOTU devices are known to need the valid altset checks, so
> > > filter out other devices.
> > > 
> > > Fixes: 93db51d06b32 ("ALSA: usb-audio: Check valid altsetting at parsing rates for UAC2/3")
> > > Reported-by: Jamie Heilman <jamie@...ible.transient.net>
> > > BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1178203
> > > Signed-off-by: Takashi Iwai <tiwai@...e.de>
> > > ---
> > >  sound/usb/format.c | 11 +++++++++++
> > >  1 file changed, 11 insertions(+)
> > > 
> > > diff --git a/sound/usb/format.c b/sound/usb/format.c
> > > index 9ebc5d202c87..e6ff317a6785 100644
> > > --- a/sound/usb/format.c
> > > +++ b/sound/usb/format.c
> > > @@ -466,6 +466,17 @@ static int validate_sample_rate_table_v2v3(struct snd_usb_audio *chip,
> > >  	unsigned int nr_rates;
> > >  	int i, err;
> > >  
> > > +	/* performing the rate verification may lead to unexpected USB bus
> > > +	 * behavior afterwards by some unknown reason.  Do this only for the
> > > +	 * known devices.
> > > +	 */
> > > +	switch (USB_ID_VENDOR(chip->usb_id)) {
> > > +	case 0x07fd: /* MOTU */
> > > +		break;
> > > +	default:
> > > +		return 0; /* don't perform the validation as default */
> > > +	}
> > > +
> > >  	table = kcalloc(fp->nr_rates, sizeof(*table), GFP_KERNEL);
> > >  	if (!table)
> > >  		return -ENOMEM;
> > 
> > Well, with this patch, while I can get it to seemingly initialize
> > without errors by replugging, I can't actually get it to work.  Jack
> > says:
> > 
> > Starting jack server...
> > JACK server starting in realtime mode with priority 10
> > self-connect-mode is "Don't restrict self connect requests"
> > Acquired audio card Audio1
> > creating alsa driver ... hw:CARD=hiFace2,DEV=0|-|1024|3|96000|0|0|nomon|swmeter|-|32bit
> > ERROR: ALSA: Cannot open PCM device alsa_pcm for playback. Falling back to capture-only mode
> > Released audio card Audio1
> > ERROR: Cannot initialize driver
> > ERROR: JackServer::Open failed with -1
> > ERROR: Failed to open server
> 
> Which kernel did you test?  There have been a few more USB-audio fixes
> that landed to Linus tree yesterday, so you'd need to test with it (in
> addition to the previous patch).

Sorry, thought that'd be clear from the alsa-info output, but yes, the
tip of Linus's tree at the time: 5.11.0-rc4-00164-g83d09ad4b950

> > here's what aplay does when it tries:
> > 
> > aplay: main:830: audio open error: Invalid argument
> > 
> > strace of that says:
> > openat(AT_FDCWD, "/dev/snd/pcmC1D0p", O_RDWR|O_NONBLOCK|O_CLOEXEC) = -1 EINVAL (Invalid argument)
> 
> Hm, it's weird that open returns -EINVAL, not the later ioctl...
> 
> > I dug up a different USB sound device (bithead) and plugged it in, it
> > still works just fine with the same commands.
> > 
> > The only difference I see in the alsa-info output is that
> > 
> >         control.7 {
> >                 iface CARD
> >                 name 'Keep Interface'
> >                 value false
> >                 comment {
> >                         access 'read write'
> >                         type BOOLEAN
> >                         count 1
> >                 }
> >         }
> > 
> > has gone missing.
> 
> This is an intended change and should be irrelevant.

Groovy.

> If the problem is still seen with the very latest Linus tree and the
> previous patch, please enable the dyndbg, e.g. pass dydbg=+p option to
> snd-usb-audio module, i.e. reload like
>    modprobe snd-usb-audio dydbg=+p
> or boot with
>    snd_usb_audio.dyndbg=+p
> boot option, retest, and give the kernel messages.

OK, updated to 5.11.0-rc4-00202-gfe75a21824e7, repatched & rebuilt with:
CONFIG_SND_DEBUG=y
CONFIG_SND_CTL_VALIDATION=y
CONFIG_DYNAMIC_DEBUG=y
CONFIG_DYNAMIC_DEBUG_CORE=y

and added dyndbg=+p to my snd-usb-audio options, dmesg after an
attempted aplay execution is attached.  For grins I built a 5.10.9
kernel with the same config to compare ... the difference between
5.10.9 and 5.11.0-rc4-00202-gfe75a21824e7 debug output is basically:


+usb 1-1.1.2: 1:1: found sync_ep=0x81, iface=1, alt=1, implicit_fb=0
 usb 1-1.1.2: 1:1: add audio endpoint 0x1
+usb 1-1.1.2: Creating new data endpoint #1
+usb 1-1.1.2: Creating new sync endpoint #81
+usb 1-1.1.2: 1:1 Set sample rate 192000, clock 40
 usb 1-1.1.2: [10] FU [M2Tech Audio 2.0 Output Playback Switch] ch = 2, val = 0/1/1
 usb 1-1.1.2: [10] FU [M2Tech Audio 2.0 Output Playback Switch] ch = 1, val = 0/1/1
 usb 1-1.1.2: RANGE setting not yet supported
 usb 1-1.1.2: [10] FU [M2Tech Audio 2.0 Output Playback Volume] ch = 2, val = -32512/0/256
 usb 1-1.1.2: RANGE setting not yet supported
 usb 1-1.1.2: [10] FU [M2Tech Audio 2.0 Output Playback Volume] ch = 1, val = -32512/0/256

...and then on 5.10.9 once I start up jackd ...

-usb 1-1.1.2: setting usb interface 1:1
-usb 1-1.1.2: Creating new playback data endpoint #1
-usb 1-1.1.2: Creating new capture sync endpoint #81
-usb 1-1.1.2: Setting params for ep #1 (type 0, 12 urbs), ret=0
-usb 1-1.1.2: Setting params for ep #81 (type 1, 4 urbs), ret=0
-usb 1-1.1.2: Starting data EP @00000000d63f36f3
-usb 1-1.1.2: Starting sync EP @00000000e9f3024b

-- 
Jamie Heilman                     http://audible.transient.net/~jamie/

View attachment "v5.11.0-rc4-00202-gfe75a21824e7-dirty-dmesg.txt" of type "text/plain" (59579 bytes)

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