On Mon, Apr 15, 2013 at 07:19:47PM +0200, Lars-Peter Clausen wrote:
This series adds a (almost) generic dmaengine PCM driver for ASoC. The tegra, spear, omap, imx, mxs, ep93xx and ux500 platforms are converted to use the generic driver instead of their own custom implementation. The driver builds on top of the dmaengine PCM library and adds the missing bits. The driver was
This all looks pretty good modulo testing and so on.
- The size of the pre-allocated audio buffer. All platforms seem use different sizes and since some of them might be sensitive to changes to the buffer size this series keeps the original size for now. But we should probably try to decide on a sane default for this and maybe allow ASoC board drivers to overwrite it somehow.
Or the platform for that matter of course.
The driver uses snd_pcm_lib_preallocate_pages to preallocate the memory buffer. snd_pcm_lib_preallocate_pages internally uses dma_alloc_coherent, while most of the platforms converted in this series use dma_alloc_writecombine. Laxman Dewangan submitted a patch[1] a couple of months ago to add support for dma_alloc_writecombine to snd_pcm_lib_preallocate_pages, I always thought the patch had been merged, but it looks like I was mistaken. So if there are concerns about performance regression due to using coherent instead of writecombine mappings we'll have to postpone converting these platforms until Laxman's patch has been merged.
Can you resend that to Takashi, it sounds like if it's not been merged it's probably due to it getting dropped rather than any great objection?