Good news: my JACK transport has been rolling for more than 2 hours without sound degradation. I'll leave it overnight just to be sure sound degradation has been fixed and not just postponed. But yes, I think I managed to engage implicit feedback sync for the playback on my Pioneer DJ DDJ-SR2. Dr. Iwai, my initial assesment was ALSA not honoring .ep_attr on quirks-table.h was the culprit for the Incompatible EP Setup messages. Turns out that for implicit feedback sync the EP is opened twice, and the ep->opened refcount prevents that. Once I commented out ep->opened++; inside snd_usb_endpoint_open on endpoint.c the kernel was able to open the EP twice(one time for data, second time for sync). I could use some help in coding an elegant way of going around the ep->opened refcount instead of simpy disabling it! Once that particular problem is sorted out I'll be able to provide a proper PATCH for all users of Pioneer gear to test implicit feedback sync. Here's the relevant dyndbg info for the success case: [35084.131891] usb 3-2: 0:1: added playback implicit_fb sync_ep 82, iface 0:1 [35084.131905] usb 3-2: Creating new data endpoint #1 [35084.131911] usb 3-2: Creating new data endpoint #82 [35084.131917] xhci_hcd 0000:00:14.0: xhci_check_bandwidth called for udev 0000000052e95692 [35084.132102] usb 3-2: 0:1 Set sample rate 44100, clock 0 [35084.132116] xhci_hcd 0000:00:14.0: xhci_check_bandwidth called for udev 0000000052e95692 [35084.132163] usb 3-2: 0:1 Set sample rate 44100, clock 0 [35084.132592] usbcore: registered new interface driver snd-usb-audio [35096.805245] usb 3-2: Open EP 0x82, iface=0:1, idx=1 [35096.805254] usb 3-2: channels=6, rate=44100, format=S24_3LE, period_bytes=9216, periods=2, implicit_fb=0 [35096.805259] usb 3-2: Setting usb interface 0:0 for EP 0x82 [35096.805264] xhci_hcd 0000:00:14.0: xhci_check_bandwidth called for udev 0000000052e95692 [35096.805475] usb 3-2: Setting usb interface 0:1 for EP 0x82 [35096.805486] xhci_hcd 0000:00:14.0: add ep 0x1, slot id 32, new drop flags = 0x0, new add flags = 0x5 [35096.805492] xhci_hcd 0000:00:14.0: add ep 0x82, slot id 32, new drop flags = 0x0, new add flags = 0x25 [35096.805495] xhci_hcd 0000:00:14.0: xhci_check_bandwidth called for udev 0000000052e95692 [35096.805499] xhci_hcd 0000:00:14.0: Adding 2 ep ctxs, 6 now active. [35096.805503] xhci_hcd 0000:00:14.0: Recalculating BW for rootport 2 [35096.805505] xhci_hcd 0000:00:14.0: Final bandwidth: 282, Limit: 1607, Reserved: 322, Available: 62 percent [35096.805510] xhci_hcd 0000:00:14.0: // Ding dong! [35096.805652] xhci_hcd 0000:00:14.0: Successful Endpoint Configure command [35096.805895] usb 3-2: 0:1 Set sample rate 44100, clock 0 [35096.805902] usb 3-2: Setting params for data EP 0x82, pipe 0x14180 [35096.805910] usb 3-2: Set up 12 URBS, ret=0 [35096.805996] usb 3-2: Open EP 0x1, iface=0:1, idx=0 [35096.806000] usb 3-2: channels=4, rate=44100, format=S24_3LE, period_bytes=6144, periods=2, implicit_fb=1 [35096.806003] usb 3-2: Open EP 0x82, iface=0:1, idx=1 [35096.806005] usb 3-2: channels=6, rate=44100, format=S24_3LE, period_bytes=9216, periods=2, implicit_fb=0 [35096.806008] usb 3-2: 0:1 Set sample rate 44100, clock 0 [35096.806011] usb 3-2: Setting params for data EP 0x1, pipe 0xc100 [35096.806018] usb 3-2: Set up 12 URBS, ret=0 [35096.806021] usb 3-2: 0:1 Set sample rate 44100, clock 0 [35096.806025] usb 3-2: Setting params for data EP 0x82, pipe 0x14180 [35096.806029] usb 3-2: Set up 12 URBS, ret=0 [35096.806048] usb 3-2: Starting data EP 0x1 (running 0) [35096.806051] usb 3-2: No URB submission due to implicit fb sync [35096.806053] usb 3-2: Starting data EP 0x82 (running 0) [35096.806076] usb 3-2: 12 URBs submitted for EP 0x82 [35096.807337] usb 3-2: Starting data EP 0x82 (running 1) [35096.807343] usb 3-2: 0:1 Start Capture PCM [35096.807346] usb 3-2: 0:1 Start Playback PCM On Sun, Mar 21, 2021 at 5:22 AM Takashi Iwai <tiwai@xxxxxxx> wrote: > > On Sun, 21 Mar 2021 05:31:11 +0100, > Geraldo wrote: > > > > Until we manage to engage implicit feedback sync for Pioneer gear I'm > > afraid the clock will drift on DUPLEX mode. > > > > I reread the Pioneer related source code and implicit feedback sync was > > disabled because it gave Incompatible EP Setup messages. I should know, I > > was a reporter on that regression. > > > > Only those messages are fake. They arise because our ALSA code it's not > > honoring .ep_attr on quirks-table.h specifically in regards to > > USB_ENDPOINT_USAGE_IMPLICIT_FB. > > That's right. The parser reads from the original descriptor, not the > one from the quirk table. That is, the implicit fb quirk has to be > declared explicitly in another quirk table. And, the implicit fb is > skipped for those devices because they didn't work; see > sound/usb/implicit.c. > > > In fact the new improved implicit feedback sync code inside pcm.c that sets > > sync upon probe is failing to set implicit_fb to 1. I commented the > > conditional for testing and I told endpoint_compatible to always return > > true. > > > > Voilà, JACK started in duplex mode without nasty Incompatible EP Setup > > problems and supposedly with implicit feedback sync on. We are not setting > > bits 5..7 of bmAttributes, at least that's what I get from the missing > > Usage field in lsusb. > > > > My JACK transport has been rolling for 17 minutes and if it goes for two > > complete hours without distortion passing-thru vinyl on Mixxxx I'll provide > > the list with a more elegant PATCH and not this gambiarra as we say on > > Brazil. > > > > Hopefully their will be implicit feedback sync for Pioneer :-) > > I know there are quite a few users with Pioneer devices around here, > so let's hope that they can test the implicit feedback things and find > the culprit of the buggy behavior. Unfortunately it's quite hard to > debug such a thing remotely without the hardware from my side. > > > Takashi > > > > > > > > On Thu, Mar 18, 2021 at 7:41 PM Geraldo <geraldogabriel@xxxxxxxxx> wrote: > > > > > > Hi everyone, > > > > > > I'm running stable kernel 5.11.6 together with my Pioneer DJ DDJ-SR2 and > > JACK. Mixxx is running on top of JACK. > > > > > > > > > After I start JACK I have about 40 minutes of good sound quality from the > > inputs. After this period the sound will begin to degrade slowly until it > > is almost pure distortion. > > > > > > The issue is gone if I restart the JACK server, no need to reboot the > > hardware. The description I gave above sounds a lot like soundcard clock > > drift (which happens to those using more than one soundcard. You know) > > which motivates me to believe we missed a bug somewhere around the recent > > changes introduced in implicit feedback sync for Pioneer devices > > > > > > Dyndbg shows nothing useful I guess. No xruns reported. > > > > > > I've recorded a 1KHz tone and after 50+ minutes the sound degradation > > kicks in. Only problem is even after cutting and encoding to mp3 128kbps > > it's still a 10 megabytes file. I suppose I could post it to Soundcloud or > > Mixcloud if anyone is interested. > > > > > > Is anyone else experiencing these symptoms with Pioneer hardware? Note > > that the sound degradation kicks in after about an hour, more or less, and > > it's for the inputs only. Outputs continue to operate fine without the need > > to restart the JACK server every hour. > > > > > > Thanks everybody, > > > Geraldo > >
