linux/sound/soc/davinci
Sudhakar Rajashekhara 5b61ea4997 ASoC: DaVinci: Fix McASP hardware FIFO configuration
On DA830/OMAP-L137 and DA850/OMAP-L138 SoCs, the McASP peripheral
has FIFO support. This FIFO provides additional data buffering. It
also provides tolerance to variation in host/DMA controller response
times. More details of the FIFO operation can be found at

http://focus.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=sprufm1&fileType=pdf

Existing sequence of steps for audio playback/capture are:
a. DMA configuration
b. McASP configuration (configures and enables FIFO)
c. Start DMA
d. Start McASP (enables FIFO)

During McASP configuration, while FIFO was being configured, FIFO
was being enabled in davinci_hw_common_param() function of
sound/soc/davinci/davinci-mcasp.c file. This generated a transmit
DMA event, which gets serviced when DMA is started.

https://patchwork.kernel.org/patch/84611/ patch clears the DMA
events before starting DMA, which is the right thing to do. But
this resulted in a state where DMA was waiting for an event from
McASP (after step c above), but the event which was already there,
has got cleared (because of step b above).

The fix is not to enable the FIFO during McASP configuration as
FIFO was being enabled as part of McASP start.

Signed-off-by: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
2010-06-15 11:53:18 +01:00
..
Kconfig DaVinci: DM365: Voice Codec support for the DM365 EVM 2010-03-12 11:12:24 +00:00
Makefile ASoC: DaVinci: Voice Codec Interface 2010-03-12 11:12:21 +00:00
davinci-evm.c DaVinci: DM365: Voice Codec support for the DM365 EVM 2010-03-12 11:12:24 +00:00
davinci-i2s.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6 2010-04-07 08:42:25 -07:00
davinci-i2s.h ALSA: Correct Vladimir Barinov's e-mail address 2008-10-10 13:41:45 +02:00
davinci-mcasp.c ASoC: DaVinci: Fix McASP hardware FIFO configuration 2010-06-15 11:53:18 +01:00
davinci-mcasp.h ASoC: DaVinci: Update suspend/resume support for McASP driver 2009-12-04 10:49:45 +00:00
davinci-pcm.c ALSA: ASoC: move dma_data from snd_soc_dai to snd_soc_pcm_stream 2010-04-05 19:14:11 +01:00
davinci-pcm.h ASoC: DaVinci: pcm, fix underrun by using sram 2009-11-19 10:48:08 +00:00
davinci-sffsdr.c ALSA: ASoC: Davinci: Updated sffsdr_hw_params() function to new format 2009-03-10 15:42:48 +00:00
davinci-vcif.c ASoC: update gfp/slab.h includes 2010-03-29 21:28:43 +02:00
davinci-vcif.h ASoC: DaVinci: Voice Codec Interface 2010-03-12 11:12:21 +00:00