Re: musb - high CPU load in DMA mode and dropouts during audio playback

[Michal Šmucr <msmucr@xxxxxxxxx>]

Hi George,

On 27.2.2014 5:15, George Cherian wrote:
> I too see the backtraces will send a patch soon to fix the same.
Thanks, i applied it and most of backtraces was suppressed.
Several times i was able to invocate it again, but this time, it was 
before complete stuck of playback application (kill -9 was only way to 
end it).
From that moment, no other audio playback can be initiated until next 
reboot. If i tried to remedy situation by replugging of USB interface, 
it leaded to nice Oops (snippet from serial console is attached).

> During my testing am not seeing the CPU usage as you mention.
That is interesting, i was able to reproduce it whenever i tried that, 
maybe it could be also some config issue.
Just for more complete info, i'm using build scripts by Robert C. Nelson 
and there are couple other patches applied to kernel before build (now 
including your previous ISOCH. handling ones) - 
https://github.com/RobertCNelson/linux-dev/tree/am33x-v3.14/patches , 
but it doesn't seems related to issue.

> Could you please share you .config.
You'll find it attached.
> I used aplay for testing playback and arecord for recording using USB
> headsets.
I tried mpd as player, but i'm able to reproduce kworker load also with 
aplay or alsa built-in speaker-test (eg. speaker-test -c 2 -D plughw:0,0).
Regarding hardware i tried few XMOS based UAC2 interfaces and recently 
also interface with TI PCM2904 USB codec, which could be very close to 
headset, you tried. It doesn't matter according to my tests.

Thanks,

Michal

Attachment: config-3.14.0-rc4-bone0.gz
Description: application/gzip

 [  176.322424] usb 2-1: USB disconnect, device number 2
[  179.654157] usb 2-1: new high-speed USB device number 3 using musb-hdrc
[  179.795133] usb 2-1: device v249c p930b is not supported
[  179.800758] usb 2-1: New USB device found, idVendor=249c, idProduct=930b
[  179.807928] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  179.815489] usb 2-1: Product: M2Tech USB Audio 2.0
[  179.820540] usb 2-1: Manufacturer: M2Tech
[  179.824901] usb 2-1: SerialNumber: 0000
[  329.707680] systemd-logind[2285]: New session 2 of user root.
[  671.601671] usb 2-1: USB disconnect, device number 3
[  671.613917] Unable to handle kernel paging request at virtual address ffffffe6
[  671.621545] pgd = c0004000
[  671.624400] [ffffffe6] *pgd=9fef6821, *pte=00000000, *ppte=00000000
[  671.631045] Internal error: Oops: 17 [#1] SMP ARM
[  671.635995] Modules linked in: usb_f_acm u_serial usb_f_ecm g_multi usb_f_mass_storage usb_f_rndis u_ether libcomposite rpcsec_gss_krb5 nfsd snd_usb_audio snd_usbmidi_lib snd_hwdep snd_seq_midi snd_seq_midi_event snd_rawmidi snd_pcm snd_seq snd_seq_device snd_timer omap_aes snd omap_sham soundcore ti_am335x_adc kfifo_buf industrialio rtc_omap uio_pdrv_genirq uio
[  671.670042] CPU: 0 PID: 19 Comm: khubd Not tainted 3.14.0-rc4-bone0 #3
[  671.676914] task: de0bf200 ti: de176000 task.ti: de176000
[  671.682622] PC is at musb_g_tx+0x9c/0x18c
[  671.686856] LR is at cppi41_trans_done+0x48/0x134
[  671.691814] pc : [<c0515354>]    lr : [<c05165c4>]    psr: a00f0193
[  671.691814] sp : de177c38  ip : 00000019  fp : c0b0ca00
[  671.703880] r10: de01eef8  r9 : 200f0193  r8 : de01e010
[  671.709378] r7 : de01eeb0  r6 : 00003400  r5 : e0878de0  r4 : ffffffcc
[  671.716242] r3 : 00000000  r2 : 00000001  r1 : e0878de2  r0 : de01e010
[  671.723109] Flags: NzCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
[  671.730887] Control: 10c5387d  Table: 9e7a0019  DAC: 00000015
[  671.736931] Process khubd (pid: 19, stack limit = 0xde176248)
[  671.742976] Stack: (0xde177c38 to 0xde178000)
[  671.747567] 7c20:                                                       de027944 de01ee84
[  671.756179] 7c40: dd281000 de01e010 00000080 200f0193 0000008a c05165c4 00000000 00000003
[  671.764790] 7c60: 00000001 c0166368 800f0093 dd399790 dd3a2b38 de027944 de01ee84 dd281000
[  671.773401] 7c80: de01e010 00000080 200f0193 c0516c44 de58ea80 c0074280 dd554580 00029903
[  671.782009] 7ca0: 00029903 00000000 00000000 00000004 dd281000 9e841720 00000080 00000001
[  671.790620] 7cc0: 0000008a c040ad88 dd2a2e80 de005900 00000021 00000000 00000000 00000000
[  671.799230] 7ce0: a00f0013 c008037c de005900 dd2a2e80 1f065000 de005900 c0a741e4 00000000
[  671.807842] 7d00: c0b11be4 00000001 00000000 a00f0013 dd390000 c0080550 00020000 de005900
[  671.816452] 7d20: c0a741e4 c0082fcc 00000021 c007fbe4 00000021 c000e244 fa200000 de177d60
[  671.825064] 7d40: 00000021 c0008578 c0511c6c c06df880 a00f0013 ffffffff de177d94 c06dffc0
[  671.833675] 7d60: de01e010 a00f0013 000034a6 0000747e de590080 de5a8800 de01e010 00008300
[  671.842286] 7d80: 00000001 00000000 a00f0013 dd390000 e0878de2 de177da8 c0511c6c c06df880
[  671.850897] 7da0: a00f0013 ffffffff 00000000 de5a8800 ffffff98 a00f0013 de6ed3ec de6ed3f0
[  671.859508] 7dc0: de62a800 c04f9d10 de26c200 00000000 de6ec000 de6ec000 000013e8 bf0cc4bc
[  671.868118] 7de0: dd4c8ac8 de6ec000 de6ec000 00000000 000013e8 00000000 00000000 bf0cc504
[  671.876729] 7e00: de6ec000 dd4c8ad0 de6eb450 de62b000 bf0dc6b4 bf0cd3e8 dd4c8a80 bf0cb3c4
[  671.885347] 7e20: bf0cb304 dd4afa20 de62a800 dd4afa00 00000000 c04fe40c c04fe3ac dd4afa20
[  671.893957] 7e40: bf0dc6b4 c0ae9b98 dd362a00 dd4afa00 00000000 c046c864 de0bf200 dd4afa54
[  671.902574] 7e60: dd4afa20 c046c8c8 dd4afa44 dd4afa20 de159530 c046c36c dd4afa20 00000000
[  671.911184] 7e80: de62a868 c0469f84 de62a800 00000000 00000000 c04fc410 00000000 de62a800
[  671.919794] 7ea0: de62a89c 00000000 de62a868 dd365400 00000000 c04f3d38 dd3664c0 dd365238
[  671.928402] 7ec0: 00000001 00000100 dd365200 dd390000 00000001 c04f66c8 00000000 00000000
[  671.937010] 7ee0: 00000003 00000000 dd365208 dd365020 00000001 dd365244 dd362a00 00000000
[  671.945621] 7f00: dd365200 dd365000 dd365020 dd365200 dd39009c 00000000 00000000 00000011
[  671.954238] 7f20: 00000000 01004280 de070001 00000000 de0bf200 c00747f8 de177f38 de177f38
[  671.962846] 7f40: 00000000 de15b280 00000000 00000000 c04f6060 00000000 00000000 00000000
[  671.971454] 7f60: 00000000 c0057b4c ffbd7fbd 00000000 ffffffff 00000000 00000000 00000000
[  671.980063] 7f80: de177f80 de177f80 00000000 00000000 de177f90 de177f90 de177fac de15b280
[  671.988671] 7fa0: c0057a74 00000000 00000000 c000d9d8 00000000 00000000 00000000 00000000
[  671.997277] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[  672.005885] 7fe0: 00000000 00000000 00000000 00000000 00000013 00000000 7ef7efff f8bfdff7
[  672.014522] [<c0515354>] (musb_g_tx) from [<c05165c4>] (cppi41_trans_done+0x48/0x134)
[  672.022778] [<c05165c4>] (cppi41_trans_done) from [<c0516c44>] (cppi41_dma_callback+0x198/0x220)
[  672.032042] [<c0516c44>] (cppi41_dma_callback) from [<c040ad88>] (cppi41_irq+0x154/0x164)
[  672.040674] [<c040ad88>] (cppi41_irq) from [<c008037c>] (handle_irq_event_percpu+0x6c/0x200)
[  672.049571] [<c008037c>] (handle_irq_event_percpu) from [<c0080550>] (handle_irq_event+0x40/0x60)
[  672.058917] [<c0080550>] (handle_irq_event) from [<c0082fcc>] (handle_level_irq+0xd4/0xfc)
[  672.067624] [<c0082fcc>] (handle_level_irq) from [<c007fbe4>] (generic_handle_irq+0x20/0x30)
[  672.076526] [<c007fbe4>] (generic_handle_irq) from [<c000e244>] (handle_IRQ+0x68/0x90)
[  672.084868] [<c000e244>] (handle_IRQ) from [<c0008578>] (omap3_intc_handle_irq+0x60/0x74)
[  672.093494] [<c0008578>] (omap3_intc_handle_irq) from [<c06dffc0>] (__irq_svc+0x40/0x50)
[  672.101998] Exception stack(0xde177d60 to 0xde177da8)
[  672.107330] 7d60: de01e010 a00f0013 000034a6 0000747e de590080 de5a8800 de01e010 00008300
[  672.115940] 7d80: 00000001 00000000 a00f0013 dd390000 e0878de2 de177da8 c0511c6c c06df880
[  672.124534] 7da0: a00f0013 ffffffff
[  672.128233] [<c06dffc0>] (__irq_svc) from [<c06df880>] (_raw_spin_unlock_irqrestore+0x1c/0x20)
[  672.137307] [<c06df880>] (_raw_spin_unlock_irqrestore) from [<c0511c6c>] (musb_urb_dequeue+0x104/0x114)
[  672.147208] [<c0511c6c>] (musb_urb_dequeue) from [<c04f9d10>] (usb_hcd_unlink_urb+0x5c/0x7c)
[  672.156233] [<c04f9d10>] (usb_hcd_unlink_urb) from [<bf0cc4bc>] (deactivate_urbs+0xb0/0xcc [snd_usb_audio])
[  672.166639] [<bf0cc4bc>] (deactivate_urbs [snd_usb_audio]) from [<bf0cc504>] (release_urbs+0x2c/0xc0 [snd_usb_audio])
[  672.177927] [<bf0cc504>] (release_urbs [snd_usb_audio]) from [<bf0cd3e8>] (snd_usb_endpoint_free+0x18/0x24 [snd_usb_audio])
[  672.189756] [<bf0cd3e8>] (snd_usb_endpoint_free [snd_usb_audio]) from [<bf0cb3c4>] (usb_audio_disconnect+0xc0/0x144 [snd_usb_audio])
[  672.202350] [<bf0cb3c4>] (usb_audio_disconnect [snd_usb_audio]) from [<c04fe40c>] (usb_unbind_interface+0x60/0x160)
[  672.213344] [<c04fe40c>] (usb_unbind_interface) from [<c046c864>] (__device_release_driver+0x7c/0xc4)
[  672.223054] [<c046c864>] (__device_release_driver) from [<c046c8c8>] (device_release_driver+0x1c/0x28)
[  672.232852] [<c046c8c8>] (device_release_driver) from [<c046c36c>] (bus_remove_device+0xdc/0xec)
[  672.242102] [<c046c36c>] (bus_remove_device) from [<c0469f84>] (device_del+0x108/0x16c)
[  672.250539] [<c0469f84>] (device_del) from [<c04fc410>] (usb_disable_device+0x84/0x1a8)
[  672.258974] [<c04fc410>] (usb_disable_device) from [<c04f3d38>] (usb_disconnect+0x80/0x170)
[  672.267773] [<c04f3d38>] (usb_disconnect) from [<c04f66c8>] (hub_thread+0x668/0xf20)
[  672.275932] [<c04f66c8>] (hub_thread) from [<c0057b4c>] (kthread+0xd8/0xec)
[  672.283274] [<c0057b4c>] (kthread) from [<c000d9d8>] (ret_from_fork+0x14/0x3c)
[  672.290884] Code: 1a00002c e8bd87f0 e3540000 08bd87f0 (e5d4301a)
[  672.315841] ---[ end trace 022736d41609c3a0 ]---
[  672.320714] Kernel panic - not syncing: Fatal exception in interrupt
[  672.327402] drm_kms_helper: panic occurred, switching back to text console