On 01/27/2014 08:40 PM, Jyri Sarha wrote:
On 01/27/2014 06:32 PM, Lars-Peter Clausen wrote:
On 01/27/2014 05:17 PM, Jyri Sarha wrote:
On 01/27/2014 05:51 PM, Lars-Peter Clausen wrote:
Hi,
I think you should try to get this in sync with the work Jean-Francois is
currently doing[1]. Having the HDMI transmitter register a CODEC device is
definitely the right approach, compared to the rather 'interesting'
constraints stuff you do in patch 4.
Oh, Jean-Francois's patches are now out. I'll take those into use, but I am
afraid it still does not save me from the constraint stuff.
The most complex piece of code comes from limited sample-rate availability,
which is coming Beaglebone-Black desing (available i2s master clock), not
from the HDMI encoder itself. It does not help with the stereo only
limitation either, because it comes from the one wire only audio data
connection on BBB.
Support for S16_LE could maybe be added if the tda998x specific codec would
fiddle with CTS_N predivider-setting (K select) according to the used sample
width. But it appears Cobox plays all the sample formats fine without this
change, so the question is if playing around with CTS_N predivider would
break already working support there (something to be tested).
The ASoC core will set the constraints for the audio format/rate to the
intersection of what is supported by the CODEC and the CPU DAI. So if the
limitation comes from the CPU DAI the constraints should be applied there
and not in the machine driver. Similar if the tda998x only supports 32 bit
samples it should advertise this and the compound card will only support 32
bit samples.
Yes. I know. But these limitations come from the run time setup of the audio
serial bus and those details are not available to the cpu dai at the register
time.
If more of the McASP configuration data would be moved to DT, instead of giving
it in set_sysclk, set_fmt, etc. calls it would be possible for the driver code
produce more accurate constraints at register time. However that would change
McASP driver a lot and would possibly break some of the legacy support.
There is nothing wrong with setting the constraints based on the parameters
passed to set_sysclk or set_fmt, etc. In fact this is something that is often
done by drivers.
- Lars
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