On Fri, 28 Sep 2018 20:03:25 +0200, Nicolas Herochao wrote: > > Hello, > > I'm writing this mail because of a Crash when connecting the B&W PX > headphones via usb. Half a year ago this used to work with Linux after > setting the default sample rate of pulseaudio to 48000k. > > A Launchpad Bug seems to describe this exact issue (detailed > description below): > https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1773697. > It pointed me to the right direction, and today I have successfully > compiled and tested a small patch that fixes the errors while also > setting the sample rate to 48000k, making these headphones plug&play > on any newer firmware. They sound awesome via USB! > > I would like to submit this patch, but it would be my first > contribution and it could potentially break the B&W PX on older > firmware. I can't test it since I see no obvious ways to downgrade the > firmware. The automatic detection of these headphones always worked > except for the sample-rate and perhaps the worst result is that old > firmware will show a non-functional microphone, like on Windows. > > So I decided to first present the patch on this mailing list and ask > for feedback and help. If anyone wants to pick the patch up, I'd > appreciate that as well. > > My questions: > > * Can a quirk somehow handle multiple firmware versions of a usb device? Currently not for a straightforward quirk table. Can we identify easily the firmware version on this device? If it's found in some id field, we can add the check and apply conditionally. > * If not: Will this quirk allow old firmware to work out of the box > but show a non-functional microphone? (And is that okay?) Yes, a good option as a quick fix for now. > Thanks for your time and any feedback you can provide! > Sincerely, > > Nicolas > > PS: more detail on the cause of the issue: > ------ > > A quirk in snd-usb-audio was added to automate setting sample rate to > 4800k and remove the previously exposed nonfunctional microphone: > 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 with the following dmesg errors: > > 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) Could you put this explanation into the patch description? > --------------- > Finally, here is the patch (based on the current mainline kernel and > generated according to all Guidelines I could find) which fixes the > quirk by removing the microphone part: ... and this one should be also merged into the patch description. > ---------------- > > From 748587283db85e219902abf4ac012864005943c8 Mon Sep 17 00:00:00 2001 > From: Nicolas Huaman <nicolas@xxxxxxxxxxx> > Date: Fri, 28 Sep 2018 18:05:15 +0200 > Subject: [PATCH 1/1] SOUND: update quirk for B&W PX to remove microphone ... what I meant is to put the explanations and other nice texts into *here*. > Signed-off-by: Nicolas Huaman <nicolas@xxxxxxxxxxx> Also, last but not least, please align the patch subject line. The prefix is like "ALSA: usb-audio:", and you can drop "1/1" if there is only one patch. The code changes look OK to me, so it'd be great if you can resubmit with the corrections above. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
