Hello, Attach USB descriptor of clock source and selectior for this earphone. AC Clock Source Descriptor: ------------------------------ Value Valuename 0x08 bLength 0x24 bDescriptorType 0x0A bDescriptorSubtype 0x09 bClockID 0x03 bmAttributes 0x07 bmControls 0x00 bAssocTerminal 0x00 iClockSource Hex dump: 0x08 0x24 0x0A 0x09 0x03 0x07 0x00 0x00 AC Clock Selector Descriptor: ------------------------------ Value Valuename 0x09 bLength 0x24 bDescriptorType 0x0B bDescriptorSubtype 0x0B bClockID 0x02 bNrInPins 0x09 baCSourceID(1) 0x0A baCSourceID(2) 0x03 bmControls 0x00 iClockSelector Hex dump: 0x09 0x24 0x0B 0x0B 0x02 0x09 0x0A 0x03 0x00 AC Clock Source Descriptor: ------------------------------ Value Valuename 0x08 bLength 0x24 bDescriptorType 0x0A bDescriptorSubtype 0x0A bClockID 0x03 bmAttributes 0x07 bmControls 0x00 bAssocTerminal 0x00 iClockSource Hex dump: 0x08 0x24 0x0A 0x0A 0x03 0x07 0x00 0x00 AC Clock Selector Descriptor: ------------------------------ Value Valuename 0x09 bLength 0x24 bDescriptorType 0x0B bDescriptorSubtype 0x0C bClockID 0x02 bNrInPins 0x09 baCSourceID(1) 0x0A baCSourceID(2) 0x03 bmControls 0x00 iClockSelector Hex dump: 0x09 0x24 0x0B 0x0C 0x02 0x09 0x0A 0x03 0x00 Thanks Chihhao On Mon, 2021-07-26 at 02:16 +0000, Geraldo Nascimento wrote: > On Sun, Jul 25, 2021 at 7:44 AM Takashi Iwai <tiwai@xxxxxxx> wrote: > > > > On Sat, 24 Jul 2021 17:04:13 +0200, > > Geraldo Nascimento wrote: > > > > > > On Sat, Jul 24, 2021 at 8:05 AM Takashi Iwai <tiwai@xxxxxxx> > > > wrote: > > > > > > > > This looks like a regression introduced by the recent commit > > > > d2e8f641257d ("ALSA: usb-audio: Explicitly set up the clock > > > > selector"), which is a fix for certain devices. Too bad that > > > > the > > > > behavior really depends on the device... > > > > > > Dr. Iwai, perhaps we could restrict the generalized fix for the > > > Behringer UFX1604 / UFX1204 with some simple logic to devices > > > that > > > only have *one* clock source. > > > > > > In that case the clock selector must be set to the only clock > > > source. > > > > > > This way we keep the generalization without breaking devices with > > > more > > > than one clock source. > > > > > > Just an idea. > > > > I don't think it's easy to generalize. All those bugs are more or > > less BIOS bugs, and a logic doesn't apply always, just because it's > > a > > bug :) For example, setting the clock selector itself should be a > > valid operation from the specification POV, while this leads to > > breakage on some devices. So, even if we add a more generic > > workaround, we need to see which side effect is more commonly seen > > at > > first. > > > > > > Takashi > > Hello, > > Like I said in one of the other emails in this thread, it's hard to > pinpoint a cause for the breakage of Samsung USBC Headset (AKG) with > VID/PID (0x04e8/0xa051) without the lsusb -v of the device in > question. > > But from the description Chihhao Chen gave in the original message, > I'm *guessing* the Clock Source for the Samsung USB Headset (AKG) > runs > at 48000hz and that we'd see a 2x Clock Multiplier in the lsusb -v > > This is all a wild guess, without the lsusb -v it's impossible to be > sure, but if I'm right then the valid setting for the Microphone's > Clock Selector is the Clock Multiplier, not the Clock Source, which, > remember, runs at half the clock, hence why Chihhao Chen sees half > the > data rate for USB IN. > > Unfortunately our kernel code presently *does* always set the Clock > Selector to the Clock Source, which is a bad assumption to make in my > humble opinion. > > The only valid case for setting the Clock Selector to the Clock > Source > is when there's precisely one Clock Selector, precisely one Clock > Source and no Clock Multipliers. > > In that special case we may be able to touch the setting of the only > Clock Selector to match the only Clock Source. > > And, frankly, the only reason we're forced to do that explicitly is > because some Behringer gear (Archwave AG DACs) gets confused and > seems > to somehow keep the old rate on the Clock Selector upon sample rate > change. > > Thank you, > Geraldo Nascimento