Hi,
Ferry Toth wrote:
> Op 20-10-2020 om 14:32 schreef Felipe Balbi:
>>
>> Hi,
>>
>> Ferry Toth <fntoth@xxxxxxxxx> writes:
>>
>> 8< snip
>>
>>>>> [ 12.657416] CR2: 0000000100000000
>>>>> [ 12.660729] ---[ end trace 9b92dea6da33c71e ]---
>>>>
>>>> It this something you can reproduce on your end? Ferry, can you get
>>>> dwc3
>>>> trace logs when this happens? ftrace_dump_on_oops may help here.
>>> I will do that tonight. Is flipping on ftrace_dump_on_oops
>>> sufficient or
>>> do I need to do more?
>>
>> you'd have to enable dwc3 trace events first ;-)
>>
>>> BTW after posting this I found in host mode dwc3 is not working
>>> properly
>>> either. No oops, but no driver get loaded on device plug in.
>>
>> okay
>>
> Ehem, you maybe only me to enable /dwc3/dwc3_ep_dequeue/enable:
>
> root@edison:/boot# uname -a
> Linux edison 5.9.0-edison-acpi-standard #1 SMP Mon Oct 19 20:17:04 UTC
> 2020 x86_64 x86_64 x86_64 GNU/Linux
> root@edison:/boot# echo 1 >
> /sys/kernel/debug/tracing/events/dwc3/dwc3_ep_dequeue/enable
> root@edison:/boot# echo 1 > /proc/sys/kernel/ftrace_dump_on_oops
> root@edison:/boot#
> root@edison:/boot# [ 2608.585323] BUG: kernel NULL pointer
> dereference, address: 0000000000000000
> [ 2608.592288] #PF: supervisor read access in kernel mode
> [ 2608.597419] #PF: error_code(0x0000) - not-present page
> [ 2608.602549] PGD 0 P4D 0
> [ 2608.605090] Oops: 0000 [#1] SMP PTI
> [ 2608.608580] CPU: 1 PID: 733 Comm: irq/15-dwc3 Not tainted
> 5.9.0-edison-acpi-standard #1
> [ 2608.616571] Hardware name: Intel Corporation Merrifield/BODEGA BAY,
> BIOS 542 2015.01.21:18.19.48
> [ 2608.625356] RIP: 0010:dwc3_gadget_ep_dequeue+0x41/0x1c0
> [ 2608.630580] Code: e9 51 01 00 00 4c 8d a3 30 01 00 00 4c 89 e7 e8
> 15 e6 42 00 49 8b 4e 48 49 89 c5 49 8d 46 48 48 8d 51 a0 48 39 c8 75
> 0f eb 2e <48> 8b 4a 60 48 8d 51 a0 48 39 c8 74 21 48 39 d5 75 ee 45 31
> f6 4c
> [ 2608.649320] RSP: 0018:ffffa838002a7c40 EFLAGS: 00010087
> [ 2608.654543] RAX: ffff9a5f4609c048 RBX: ffff9a5f46f48028 RCX:
> 0000000000000000
> [ 2608.661666] RDX: ffffffffffffffa0 RSI: 0000000000000008 RDI:
> ffff9a5f46f48158
> [ 2608.668790] RBP: ffff9a5f7bd09b40 R08: 00000000000002d8 R09:
> ffff9a5f7dd6a000
> [ 2608.675913] R10: ffffa838002a7d90 R11: ffff9a5f46f48300 R12:
> ffff9a5f46f48158
> [ 2608.683039] R13: 0000000000000046 R14: ffff9a5f4609c000 R15:
> ffff9a5f7ad77e00
> [ 2608.690165] FS: 0000000000000000(0000) GS:ffff9a5f7e300000(0000)
> knlGS:0000000000000000
> [ 2608.698244] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 2608.703980] CR2: 0000000000000000 CR3: 000000003780a000 CR4:
> 00000000001006e0
> [ 2608.711102] Call Trace:
> [ 2608.713561] usb_ep_dequeue+0x19/0x80
> [ 2608.717234] u_audio_stop_capture+0x54/0x9a [u_audio]
> [ 2608.722289] afunc_set_alt+0x73/0x80 [usb_f_uac2]
I took a look at how the audio function is handling switching alternate
setting and dequeuing endpoints, and I think I found the issue.
Here's a snippet of the free_ep() code in u_audio.c:
static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
{
.....
for (i = 0; i < params->req_number; i++) {
if (prm->ureq[i].req) {
usb_ep_dequeue(ep, prm->ureq[i].req);
usb_ep_free_request(ep, prm->ureq[i].req);
prm->ureq[i].req = NULL;
}
}
....
usb_ep_dequeue() can be asynchronous. The dwc3 still has ownership of
the request until it gives back the request. Freeing the request
immediately here will cause a problem.
BR,
Thinh
