Using a higher bitclk then expected doesn't always work. Here is an example:
aplay -Dhw:0,0 -d 5 -r 48000 -f S24_LE -c 2 audio48k24b2c.wav
In this case, the required bitclk is 48000 * 24 * 2 = 2304000 but the closest bitclk that can be derived is 3072000. Since the clock is faster than expected, it will start to send bytes from the next channel so the sound will be corrupted.
Fixes: 82bab88910ee ("ASoC: codec: wm8960: Relax bit clock computation when using PLL") Fixes: 3c01b9ee2ab9 ("ASoC: codec: wm8960: Relax bit clock computation") Signed-off-by: Daniel Baluta daniel.baluta@nxp.com Signed-off-by: Shengjiu Wang shengjiu.wang@nxp.com
I think this is probably going to need a much more involved fix. The problem is that there are systems that depend on this behaviour, so you can't just flat out revert it. And to be fair the I2S specification says that bit clock can run at a higher rate than required for the data, so the behaviour is correct as well.
Probably the best solution here is to add additional contraints from the machine driver on which rates/bit depths/channels are supported.
Just double check the issue, the real reason is in below:
The call sequence in wm8960_configure_clocking is
ret = wm8960_configure_sysclk(); if (ret >= 0) goto configure_clock;
....
ret = wm8960_configure_pll();
configure_clock: ...
wm8960_configure_sysclk is called before wm8960_configure_pll, as there is bitclk relax on both functions, so wm8960_configure_sysclk always return success, then wm8960_configure_pll() never be called.
So bitclk relax condition should be removed in wm8960_configure_sysclk, That wm8960_configure_pll can be called, and there is also bitclk relax function in wm8960_configure_pll.
I will update and resend this patch.
Best regards Wang shengjiu