https://github.com/torvalds/linux
Revision 982b604bc56a3da874e489051fc7adb49b1eba65 authored by Russell King on 20 November 2012, 12:18:52 UTC, committed by Mark Brown on 21 November 2012, 01:38:39 UTC
Stress testing the driver with multiple start/stop events causes
kirkwood-dma to report underrun errors (which used to cause the kernel
to lock up solidly).  This is because kirkwood-i2s is not respecting
the restrictions imposed on clearing the 'pause' bit.  Follow what the
spec says; the busy bit must be read as being clear twice before the
pause bit can be released.  This solves the underruns.

However, it has been noticed that the busy bit occasionally does not
clear itself, hence the waiting is bounded to 5ms maximum to avoid a
new reason for the kernel to lockup.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
1 parent 2424d45
History
Tip revision: 982b604bc56a3da874e489051fc7adb49b1eba65 authored by Russell King on 20 November 2012, 12:18:52 UTC
ASoC: kirkwood-i2s: fix DMA underruns
Tip revision: 982b604
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