BCM2708/ASoC: Add Mbed audio board support

[kfigiela]

(Almost) copy-paste merge from 3.8 branch.

[koalo]

Thank you!
Have you tested it?

[kfigiela]

Yes, it is working fine :)

The only issue is that I get some DMA warnings in dmesg, but playback still works:

[ 4364.432611] bcm2708-dmaengine bcm2708-dmaengine: DMA transfer could not be terminated

[kfigiela]

I'm not sure why github shows here my another commit, but this one (d16f542) shouldn't be merged.

[koalo]

Github adds commits to the pull request as long as you push them to the same branch and the pull request is not merged, yet. The DMA error seems like a bug in my DMA driver - I will have a look at it.

[koalo]

Could you please try to increase the timeout in this line:
https://github.com/koalo/linux/blob/rpi-3.10.y/drivers/dma/bcm2708-dmaengine.c#L380

E.g. to 10000

[kfigiela]

I've increased timeout to 10 000 and no warnings so far. I will give you more feedback on that tomorrow evening.

[kfigiela]

Ok, no warnings after whole day. Increasing the timeout fixed the issue.

[koalo]

Thank you very much for reporting and testing!

[koalo]

Regarding the original request: I haven't merged this, because I was about to submit the driver to raspberrypi/linux. Please rebase it and submit the pull request there.

[kfigiela]

Ok, will do it next week.