Linux/PROCESSOR-SDK-AM335X: MUSB PIO Mode

Hi Shin,

Have you tried hardcoding use_dma to 0 in musb_core.c?

Best Regards,
Yordan

Hi Yordan,

I did it. It looks dma mode is disabled but problem is same with UAC2.

When start UAC2 then message shown like this.

[ 414.952521] sched: RT throttling activated
[ 434.262561] INFO: rcu_preempt detected stalls on CPUs/tasks:
[ 434.268787] (detected by 0, t=2102 jiffies, g=21722, c=21721, q=11)
[ 434.275797] All QSes seen, last rcu_preempt kthread activity 2102 (13426-11324), jiffies_till_next_fqs=1, root ->qsmask 0x0
[ 434.287297] Main R running 0 1191 1039 0x00000002
[ 434.294195] Backtrace:
[ 434.297496] [<c00134e4>] (dump_backtrace) from [<c00136e0>] (show_stack+0x18/0x1c)
[ 434.305396] r7:c0914754 r6:c0914328 r5:0000040f r4:cbdbe100
[ 434.312188] [<c00136c8>] (show_stack) from [<c0055c74>] (sched_show_task+0xbc/0x110)
[ 434.320550] [<c0055bb8>] (sched_show_task) from [<c0077950>] (rcu_check_callbacks+0x8c8/0x8d4)
[ 434.329469] r5:c0914328 r4:c09147ac
[ 434.333822] [<c0077088>] (rcu_check_callbacks) from [<c007ac80>] (update_process_times+0x44/0x6c)
[ 434.342989] r10:c091530c r9:c008a098 r8:00000000 r7:00000065 r6:00000000 r5:cbdbe100
[ 434.351787] r4:ffffe000
[ 434.354889] [<c007ac3c>] (update_process_times) from [<c008a094>] (tick_sched_handle+0x50/0x54)
[ 434.363886] r7:00000065 r6:1bf1395d r5:cafddaa8 r4:c0915a40
[ 434.370494] [<c008a044>] (tick_sched_handle) from [<c008a0fc>] (tick_sched_timer+0x64/0xb8)
[ 434.379406] [<c008a098>] (tick_sched_timer) from [<c007b9d0>] (__hrtimer_run_queues.constprop.6+0x150/0x1e0)
[ 434.389540] r7:c0915300 r6:cafdc000 r5:c0915a40 r4:c09152c0
[ 434.396262] [<c007b880>] (__hrtimer_run_queues.constprop.6) from [<c007bc90>] (hrtimer_interrupt+0xb4/0x250)
[ 434.406395] r10:c0915378 r9:cafdd978 r8:ffffffff r7:7fffffff r6:00000003 r5:cafdc000
[ 434.415185] r4:c09152c0
[ 434.418370] [<c007bbdc>] (hrtimer_interrupt) from [<c0020dac>] (omap2_gp_timer_interrupt+0x30/0x38)
[ 434.427707] r10:c0954794 r9:cb804c00 r8:00000010 r7:00000000 r6:00000000 r5:cb804c10
[ 434.436484] r4:c090ccb4
[ 434.439641] [<c0020d7c>] (omap2_gp_timer_interrupt) from [<c006b694>] (handle_irq_event_percpu+0xb4/0x16c)
[ 434.449823] [<c006b5e0>] (handle_irq_event_percpu) from [<c006b7b0>] (handle_irq_event+0x64/0x90)
[ 434.458994] r10:c0956140 r9:00000010 r8:cb806000 r7:cafddbb0 r6:00000000 r5:cb804c10
[ 434.467768] r4:cb804c00
[ 434.470878] [<c006b74c>] (handle_irq_event) from [<c006e58c>] (handle_level_irq+0xb8/0x168)
[ 434.479520] r5:cb804c10 r4:cb804c00
[ 434.483795] [<c006e4d4>] (handle_level_irq) from [<c006ad5c>] (generic_handle_irq+0x2c/0x3c)
[ 434.492511] r5:00000010 r4:c092bf84
[ 434.496779] [<c006ad30>] (generic_handle_irq) from [<c006afc8>] (__handle_domain_irq+0x5c/0xb0)
[ 434.505981] [<c006af6c>] (__handle_domain_irq) from [<c0009468>] (omap_intc_handle_irq+0x3c/0x98)
[ 434.515141] r9:00000010 r8:cb806000 r7:cafddadc r6:ffffffff r5:600b0113 r4:c0985a40
[ 434.524016] [<c000942c>] (omap_intc_handle_irq) from [<c0014194>] (__irq_svc+0x54/0x90)
[ 434.532348] Exception stack(0xcafddaa8 to 0xcafddaf0)
[ 434.537882] daa0: 00404140 00000101 c0956100 00000000 00000002 00000010
[ 434.546607] dac0: 00000000 00000000 cb806000 00000010 c0956140 cafddb54 c0956140 cafddaf8
[ 434.555198] dae0: c0035304 c0034e48 600b0113 ffffffff
[ 434.560505] r5:600b0113 r4:c0034e48
[ 434.564861] [<c0034dac>] (__do_softirq) from [<c0035304>] (irq_exit+0xec/0x120)
[ 434.572452] r10:cab6b80c r9:00000010 r8:cb806000 r7:00000000 r6:00000000 r5:00000010
[ 434.581237] r4:c092bf84
[ 434.584314] [<c0035218>] (irq_exit) from [<c006afcc>] (__handle_domain_irq+0x60/0xb0)
[ 434.592423] r5:00000010 r4:c092bf84
[ 434.596675] [<c006af6c>] (__handle_domain_irq) from [<c0009468>] (omap_intc_handle_irq+0x3c/0x98)
[ 434.605833] r9:00000010 r8:cbd4a010 r7:cafddbe4 r6:ffffffff r5:200b0013 r4:c0985a40
[ 434.614708] [<c000942c>] (omap_intc_handle_irq) from [<c0014194>] (__irq_svc+0x54/0x90)
[ 434.623023] Exception stack(0xcafddbb0 to 0xcafddbf8)
[ 434.628482] dba0: d0d88410 d0d88412 000034a6 600b0013
[ 434.637200] dbc0: cab6b800 caf59500 00000000 ca93e600 cbd4a010 00000010 cab6b80c cafddc5c
[ 434.645853] dbe0: cafddb80 cafddc00 bf1bbaa0 bf1bcf10 200b0013 ffffffff
[ 434.652737] r5:200b0013 r4:bf1bcf10
[ 434.661932] [<bf1bcc48>] (musb_urb_enqueue [musb_hdrc]) from [<bf134280>] (usb_hcd_submit_urb+0xb4/0x8ac [usbcore])
[ 434.672721] r10:c5045a00 r9:00000000 r8:02080020 r7:00000000 r6:ca93e600 r5:caf59508
[ 434.681515] r4:caf59500
[ 434.690021] [<bf1341cc>] (usb_hcd_submit_urb [usbcore]) from [<bf135be4>] (usb_submit_urb+0x2b8/0x4cc [usbcore])
[ 434.700526] r10:c5045a00 r9:00000000 r8:00000004 r7:00000001 r6:c5047800 r5:02080020
[ 434.709298] r4:caf59500
[ 434.717211] [<bf13592c>] (usb_submit_urb [usbcore]) from [<bf3039c0>] (snd_usb_endpoint_start+0x12c/0x344 [snd_usb_audio])
[ 434.728584] r10:c5045a00 r9:caf59500 r8:02080020 r7:cace0000 r6:00000000 r5:cace1000
[ 434.737373] r4:cace0000
[ 434.743081] [<bf303894>] (snd_usb_endpoint_start [snd_usb_audio]) from [<bf30c044>] (start_endpoints+0xe8/0x17c [snd_usb_audio])
[ 434.754969] r10:c5045a00 r9:cafdc000 r8:00000001 r7:cace1000 r6:00000001 r5:caf69800
[ 434.763743] r4:c5045410
[ 434.769390] [<bf30bf5c>] (start_endpoints [snd_usb_audio]) from [<bf30deb4>] (snd_usb_pcm_prepare+0x338/0x3f8 [snd_usb_audio])
[ 434.781114] r6:00000000 r5:caf69800 r4:c5045410
[ 434.788007] [<bf30db7c>] (snd_usb_pcm_prepare [snd_usb_audio]) from [<c052b544>] (snd_pcm_do_prepare+0x1c/0x34)
[ 434.798428] r10:c5045a00 r9:cafdc000 r8:00000001 r7:00000002 r6:c5045a00 r5:c094b9a8
[ 434.807220] r4:c5045a00
[ 434.810332] [<c052b528>] (snd_pcm_do_prepare) from [<c052b13c>] (snd_pcm_action_single+0x40/0x88)
[ 434.819506] r5:c094b9a8 r4:c5045a00
[ 434.823815] [<c052b0fc>] (snd_pcm_action_single) from [<c052b1e8>] (snd_pcm_action_nonatomic+0x64/0x6c)
[ 434.833505] r7:00000029 r6:00000002 r5:c094b9a8 r4:c5045a00
[ 434.840217] [<c052b184>] (snd_pcm_action_nonatomic) from [<c052da80>] (snd_pcm_common_ioctl1+0xa84/0xf58)
[ 434.850074] r7:00000029 r6:00000002 r5:cac62cb8 r4:00000000
[ 434.856762] [<c052cffc>] (snd_pcm_common_ioctl1) from [<c052e1d8>] (snd_pcm_playback_ioctl1+0x284/0x60c)
[ 434.866540] r10:00000000 r9:cafdc000 r8:00000001 r7:00000029 r6:ca9680c0 r5:00000001
[ 434.875319] r4:c5045a00
[ 434.878453] [<c052df54>] (snd_pcm_playback_ioctl1) from [<c052e58c>] (snd_pcm_playback_ioctl+0x2c/0x38)
[ 434.888136] r8:00000001 r7:00000029 r6:ca9680c0 r5:caea1850 r4:00000001
[ 434.896007] [<c052e560>] (snd_pcm_playback_ioctl) from [<c0116538>] (do_vfs_ioctl+0x480/0x6f8)
[ 434.905103] [<c01160b8>] (do_vfs_ioctl) from [<c01167ec>] (SyS_ioctl+0x3c/0x64)
[ 434.912690] r10:00000000 r9:cafdc000 r8:00000001 r7:00004140 r6:ca9680c0 r5:00000029
[ 434.921474] r4:ca9680c1
[ 434.924574] [<c01167b0>] (SyS_ioctl) from [<c000fa00>] (ret_fast_syscall+0x0/0x3c)
[ 434.932435] r9:cafdc000 r8:c000fbc4 r7:00000036 r6:b45fe2bc r5:0006c0ee r4:007e3318
[ 434.941313] rcu_preempt kthread starved for 2102 jiffies! g21722 c21721 f0x2 s3 ->state=0x0

Hi,

It seems that some real-time task is started in your system:
[ 414.952521] sched: RT throttling activated
[ 434.262561] INFO: rcu_preempt detected stalls on CPUs/tasks:

Are you using the RT kernel or the non-RT one?

Also can you share your full boot log & your dts file?

Best Regards,
Yordan