Hi Michal,
On 2/26/2014 7:07 PM, Michal Šmucr wrote:
On 18.2.2014 2:18, Michal Šmucr wrote:
Hello,
i'm fighting with audio playback problem on Beaglebone Black AM-3358.
Class compilant USB soundcards with isochronous transfers.
what is the application you are using for play back.
With DMA enabled in kernels 3.13.2 and 3.14-rc2 it has following
symptoms.
- it will stutter immediately after starts of playback
- kworker thread shows about 80-90% CPU usage during playback
- it presents with cppi41_dma_control warnings and traces, plus couple
of transfer errors
(i've enabled also CONFIG_DMADEVICES_DEBUG, so it dmesg is quite
lengthy)
http://vpub.smucr.cz/pub/bbb/debug/dmesg.log
I too see the backtraces will send a patch soon to fix the same.
During my testing am not seeing the CPU usage as you mention.
Could you please share you .config.
I used aplay for testing playback and arecord for recording using USB
headsets.
With force PIO at any tested kernel from 3.8.x to 3.14.x and DMA mode at
3.12.9 it is better, CPU load seems to be much lower, but it is not
completely solved. Still during high interrupt load from other devices
like NIC or second USB port, i'm having audio dropouts. Without any
messages this time.
I tested to apply following George Cherian's related patches
http://marc.info/?l=linux-usb&m=139081552015728&w=2
usb: musb: musb_host: Enable ISOCH IN handling for AM335x host
usb: musb: musb_cppi41: Make CPPI aware of high bandwidth transfers
usb: musb: musb_cppi41: Handle ISOCH differently and not use the hrtimer
and Adam Wozniak's
http://marc.info/?l=linux-usb&m=139101388408467&w=2
"high cpu load on omap3 using musb"
I also tried to find something related in TI git tree and compile
linux-next, but without luck.
Any tips, what to do next? Does anybody experienced same issue?
Thanks,
Michal
--
-George
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