On 2019/09/09 9:31, Kuninori Morimoto wrote:
Hi Katsuhiro
This patch set 0Hz to sysclk when shutdown the card.
Some codecs set rate constraints that derives from sysclk. This mechanism works correctly if machine drivers give fixed frequency.
But simple-audio and audio-graph card set variable clock rate if 'mclk-fs' property exists. In this case, rate constraints will go bad scenario. For example a codec accepts three limited rates (mclk / 256, mclk / 384, mclk / 512).
Bad scenario as follows (mclk-fs = 256): - Initialize sysclk by correct value (Ex. 12.288MHz) - Codec set constraints of PCM rate by sysclk 48kHz (1/256), 32kHz (1/384), 24kHz (1/512) - Play 48kHz sound, it's acceptable - Sysclk is not changed
- Play 32kHz sound, it's acceptable - Set sysclk to 8.192MHz (= fs * mclk-fs = 32k * 256) - Codec set constraints of PCM rate by sysclk 32kHz (1/256), 21.33kHz (1/384), 16kHz (1/512) - Play 48kHz again, but it's NOT acceptable because constraints do not allow 48kHzSo codecs treat 0Hz sysclk as signal of applying no constraints to avoid this problem.
Signed-off-by: Katsuhiro Suzuki katsuhiro@katsuster.net
I'm not 100% understand your issue. .hw_params (= set mclk/sysclk) is not called in bad case ?? Or it is called but Codec driver ignores it somehow ??
Ah, sorry for confusing. It's not either. hw_params() of machine driver has been called even if constraints don't have a requested PCM rate. But it's not expected.
For example, if constraints are 32k, 21.33k, 16k, hw_params() will be called with 32k when an user requests to play 48k sounds.
Thank you for your help !! Best regards
Kuninori Morimoto
Best Regards, Katsuhiro Suzuki