[alsa-devel] mcasp: stream has more channels (2) than are enabled in mcasp (0)

[Rick Mann]

> On Apr 18, 2016, at 08:36 , Peter Ujfalusi <peter.ujfalusi at ti.com> wrote:
> 
> On 04/04/2016 11:59 AM, Rick Mann wrote:
>> I've got a Beaglebone Green with a custom cape (CODEC and amp and some
>> other stuff).
>> 
>> Kernel 4.4.6-bone-rt-r6. When I load the overlay that should set up my
>> CODEC in the device tree, I get the following in the log.
>> 
>> [  367.172337] davinci-mcasp 48038000.mcasp: stream has more channels (2)
>> than are enabled in mcasp (0) [  367.172374] davinci-mcasp 48038000.mcasp:
>> ASoC: can't set 48038000.mcasp hw params: -22
>> 
>> You can see a little more log context, along with the DTS, here:
>> 
>> http://pastebin.com/UPB1xjPF
>> 
>> Can anyone tell me what this means? Thanks!
> 
> The fragment mostly looks OK, but am335x have 4 serializers, not 16 and the
> num-serializer is deprecated at least in upstream kernel.
> 
> Something goes wrong when the McASP is loaded for sure, some parameters did
> not got updated via DT perhaps, or most likely the DT fragment is loaded after
> the McASP is loaded.
> Can you print out:
> slots, max_active_serializers, active_serializers and channels in
> mcasp_common_hw_param() function?
> Also just in case, can you put a dev_err() print in davinci_mcasp_probe() to
> see when the driver is loaded compared to the time when the fragment is loaded?
> 
> If McASP is built in, try to build it as module and load the audio modules
> after the DT fragments are handled.

Thanks for the suggestions, Peter, I really appreciate the help. Here's what I get:

[  256.743991] davinci-mcasp 48038000.mcasp: Slots: 2, max_active_serializers: 1, active_serializers: 0, channels: 2

I rebuilt the 4.4.7-bone-rt-r9 kernel using Robert C Nelson's bb-kernel repo scripts. I modified sound/soc/davinci/davinci-mcasp.c to print some diagnostics. Rebooted, then executed the following. Note that BB-BONE-AUDI-02.dts is <https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-BONE-AUDI-02-00A0.dts>, and the base DTB is <http://pastebin.com/5vVEdAKt>:

$ sudo su
# echo BB-BONE-AUDI-02 > $SLOTS
# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: B [AudioCape Rev B], device 0: davinci-mcasp.0-tlv320aic3x-hifi tlv320aic3x-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
# speaker-test 

speaker-test 1.0.28

Playback device is default
Stream parameters are 48000Hz, S16_LE, 1 channels
Using 16 octaves of pink noise
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 16 to 32768
Period size range from 8 to 16384
Using max buffer size 32768
Periods = 4
Unable to set hw params for playback: Invalid argument
Setting of hwparams failed: Invalid argument

speaker-test caused the following to be logged:

[  256.743991] davinci-mcasp 48038000.mcasp: Slots: 2, max_active_serializers: 1, active_serializers: 0, channels: 2
[  256.754343] davinci-mcasp 48038000.mcasp: ASoC: can't set 48038000.mcasp hw params: -22


Full logs:

	http://pastebin.com/HGhu9CPk




-- 
Rick Mann
rmann at latencyzero.com