ASoC: soc-pcm: add symmetry for channels and sample bits
Some SoCs can only work in mono or stereo mode at one time. So if we let them capture a mono stream while playing a stereo stream, there might be a problem occur to one of these two streams: double paced or slowed down. In soc-pcm.c, we have soc_pcm_apply_symmetry() to apply the rate symmetry. But we don't have one for channels. Likewise, we can treat symmetric_rate as a solution for those SoCs or CODECs which can not handle asymmetrical LRCLK. But it's also impossible for them to handle asymmetrical BCLK. And accodring to BCLK = LRCLK * channel number * slot size(fixed or sample bits), sample bits might also be a problem if they are not using a fixed slot size. Thus, this patch applys symmetry for channels and sample bits. Meanwhile, there might be a race between two substreams if starting simultaneously. Previously, we only added warning to compalin but still using conservative way to let it carry on. However, this patch rejects the second stream with any unmatched parameter to make sure the first existing stream won't be broken. Signed-off-by: NNicolin Chen <b42378@freescale.com> Signed-off-by: NMark Brown <broonie@linaro.org>
Showing
想要评论请 注册 或 登录