[alsa-devel] [RFC PATCH 0/5] OMAP/ASoC: McBSP: FIFO handling related fixes

[Peter Ujfalusi]

And I managed to mistype linux-omap...
Resending.
Sorry for the noise.

-- 
Péter


On Monday 31 May 2010 11:03:21 Ujfalusi Peter (Nokia-D/Tampere) wrote:
> Hello,
> 
> This series aims to correct how the McBSP FIFO is viewed, and handled.
> 
> Introduction of the problem:
> OMAP McBSP FIFO is word structured:
> McBSP2 has 1024 + 256 = 1280 word long buffer,
> McBSP1,3,4,5 has 128 word long buffer
> 
> This means, that the size of the FIFO
> depends on the McBSP word size configuration.
> For example on McBSP3:
> 16bit samples: size is 128 * 2 = 256 bytes
> 32bit samples: size is 128 * 4 = 512 bytes
> It is simpler to place constraint for buffer and period based on channels.
> McBSP3 as example again (16 or 32 bit samples):
> 1 channel (mono): size is 128 frames (128 words)
> 2 channels (stereo): size is 128 / 2 = 64 frames (2 * 64 words)
> 4 channels: size is 128 / 4 = 32 frames (4 * 32 words)
> 
> Since now the McBSP codec supports not only 16bit samples (32biut has been
> recently added), the FIFO size handling is no longer correct, since it has
> been hard wired for 16bit word length.
> 
> The series changes how the users of McBSP are configuring the FIFO:
> It used to be 0 based (0 meant 1 word threshold). After this series users
> can configure the threshold in 1 base mode (1 means 1 word threshold). The
> platform code now provides the _full_ size of the FIFO in words, instead
> of the already limited value used in the past.
> 
> In ASoC omap-mcbsp code hw_rule based constraint refinement is going to be
> used instead of the hardwired static constraint, which was correct only in
> case of 16bit word length.
> 
> The hw_rule is refining the minimum buffer size based on the channel number
> going to be used by the coming stream.
> In case of threshold mode additional hw_rule refines the maximum allowed
> period size.
> 
> The series are generated agains Takashi's sound-2.6: topic/asoc branch.
> 
> CCing also Eduardo, and Eero since they have worked on the original
> FIFO/threshold implementation.
> 
> All commetns and testers are welcome!
> Peter
> 
> ---
> Peter Ujfalusi (5):
>   OMAP: McBSP: Function to query the FIFO size
>   OMAP3: McBSP: Change the way how the FIFO is handled
>   OMAP3: McBSP: Use the port's buffer_size when calculating tx delay
>   ASoC: omap-mcbsp: Save, and use wlen for threshold configuration
>   ASoC: omap-mcbsp: Place correct constraints for streams
> 
>  arch/arm/mach-omap2/mcbsp.c             |   10 ++--
>  arch/arm/plat-omap/include/plat/mcbsp.h |    2 +
>  arch/arm/plat-omap/mcbsp.c              |   31 ++++++---
>  sound/soc/omap/omap-mcbsp.c             |  112
> +++++++++++++++++++++++------- 4 files changed, 114 insertions(+), 41
> deletions(-)
> 
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