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Noise occurs when playback via USB 2.0 and USB Audio 1.0 devices with BeagleBone Black and SDK 7.00.00.00

Satoshi TOMINAGA
Intellectual 850 points

I meet the problem when BeagleBone Black is connected with USB audio device which specification is USB 2.0 and USB Audio 1.0.

I want to know how to avoid the situation.
If there are any patches or workarounds, please let me know.

Condition:
- TI SDK 07.00.00.00
- kernel is configured with Disable DMA (always use PIO) for MSUB DMA mode.

USB audio device connection:
- USB 2.0 and USB Audio 1.0 devices are connected to USB port directory or via USB-2.0 HUB.
"USB 2.0 and USB Audio 1.0 device" uses USB High-Speed, but audio profile is USB Audio 1.0, so these devices works without vendor-specified driver on Windows OS.
e.g. Yamaha YVC-1000
- http://www.yamaha.com/products/en/communication/usb_conference_speakerphones/yvc-1000/

Steps for reproduction:
- Play audio using aplay.

Result:
- Playback sound is noisy. Waveform has periodical 20 msecs gap within every 100 to 200 msec.

Additional information:
- When USB 1.1 HUB is inserted between BBB and the device, noise does not occur.
- No noise observed on capture (recording) side.
- By observing USB packets by USB analyzer, normally the interval of render packets is 1 msec. But once in 6 to 8 packets, the interval becomes 1.25 msecs, one additional sub frame duration.
- For capture side, the interval is always 1 msec.

Consideration:
- I think some problem on packet scheduling.

  • 0
    Intellectual 850 points

    Hi,

    I want to try the situation BBB build-in USB hub as USB 1.1 hub.

    Are there any kernel configuration or boot option?

    I already tried uncheck xHCI HCD (USB 3.0) support / EHCI HCD (USB 2.0) support, but the result is the same.

    I find that Raspberry Pi can do by inserting line "dwc_otg.speed=1" to /boot/cmdline.txt

    TOMINAGA 'Tommy' Satoshi

  • 0 in reply to Satoshi TOMINAGA
    TI__Guru**** 168211 points

    SDK7.0 kernel does not have an option for that, but the following patch will force the AM335x USB controller to work in full-speed mode.

    diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index b841ee0..202615c 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -948,7 +948,6 @@ void musb_start(struct musb *musb)
 
        /* put into basic highspeed mode and start session */
        musb_writeb(regs, MUSB_POWER, MUSB_POWER_ISOUPDATE
-                       | MUSB_POWER_HSENAB
                        /* ENSUSPEND wedges tusb */
                        /* | MUSB_POWER_ENSUSPEND */
                   );
  • 0 in reply to Bin Liu
    Intellectual 850 points

    HI Bin,

    Thank you for your information.

    The patch works for my issue!

    The sound from YVC-1000 is clear with the patch.

    Regards,

    Tommy

  • 0
    Intellectual 850 points

    For original questing,

    The situation does not occur with Raspberry Pi, and the implementation already solved the problem.

    http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=39175

    https://github.com/ghollingworth/linux/commit/cc68e81acc17773029333dd3a0201ef347ab0b38

    But this patch is just for Raspberry PI depended OTG driver.

    Are there any hints to apply this patch for BBB?

    Regards,

    Tommy