[alsa-devel] [PATCH] ALSA: usb-audio: update quirk for B&W PX to remove microphone

[Takashi Iwai]

On Fri, 05 Oct 2018 00:31:47 +0200,
Nicolas Herochao wrote:
> 
> Hey, Thanks for the quick response
> 
> Am 04.10.18 um 22:55 CEST schrieb Takashi Iwai:
> 
> > On Thu, 04 Oct 2018 16:42:05 +0200,
> > Nicolas Huaman wrote:
> >> A quirk in snd-usb-audio was added to automate setting sample rate to
> >> 4800k and remove the previously exposed nonfunctional microphone for
> >> the Bowers & Wilkins PX:
> >> commit 240a8af929c7c57dcde28682725b29cf8474e8e5
> >> https://lore.kernel.org/patchwork/patch/919689/
> >>
> >> However the headphones where updated shortly after that to remove the
> >> unintentional microphone functionality. I guess because of this the
> >> headphones now crash when connecting them via USB while the quirk is
> >> active. Dmesg:
> >>
> >> snd-usb-audio: probe of 2-3:1.0 failed with error -22
> >> usb 2-3: 2:1: cannot get min/max values for control 2 (id 2)
> >>
> >> This patch removes the microfone and allows the headphones to connect
> >> and work out of the box. It is based on the current mainline kernel
> >>   and successfully applied an tested on my machine (4.18.10.arch1-1).
> >>
> >> Signed-off-by: Nicolas Huaman <nicolas at herochao.de>
> > Thanks, that looks much better now, and I can apply it.
> >
> > But just to be sure: is any quirk required after the firmware update
> > on this device at all?  What happens if you remove the whole quirk?
> 
> Yes, the sample-rate problem is still present. I initially tried
> disabling the quirk, but then I needed to set the default sample rate
> of pulse to 48k again for the headphones to play sound, which is why I
> wanted to find out how to fix it completely.
> 
> This problem doesn't appear on windows (I think windows defaults to
> 48k?). Perhaps that's the reason why it wasn't patched in a firmware
> update up until now.
> 
> > If this modified quirk is still mandatory, I'll happily apply the
> > patch.
> >
> >
> > thanks,
> >
> > Takashi
> 
> The headphones I got already had the fixed firmware version, but even
> older headphones can be updated using Android, IOS or Windows.
> 
> My Fix corrects detection for headphones with all Firmware after
> February 2018, so I think this quirk probably presents the best
> solution for now, especially since the nonfunctional microphone of
> older Firmware appeared on all platforms.

Fair enough, I merged the patch now.
Thanks!


Takashi