Hello,
Changes since RFC v2: - Comments added explaining the changes, and documenting the API in patch2 - In patch5: - Variable names changed in the hw_rule function - hw_rule function got renamed - The snd_pcm_hw_rule_add calls moved so it anly got set on OMAP3
Intro mail from the previous series:
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 OMAP2: McBSP: Change the way how the FIFO is handled OMAP2: 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 | 51 ++++++++++----- sound/soc/omap/omap-mcbsp.c | 113 ++++++++++++++++++++++++------- 4 files changed, 129 insertions(+), 47 deletions(-)