At Mon, 21 Jul 2014 10:01:22 +0100, Richard Fitzgerald wrote:
On Thu, Jul 17, 2014 at 08:42:15PM +0100, Mark Brown wrote:
On Wed, Jul 16, 2014 at 01:10:39PM +0100, Richard Fitzgerald wrote:
If we don't disable the AIF TX/RX then we may fall into a situation where the new AIF settings are ignored by the device. For example, this problem manifests when switching between different sample rates.
So, what this does is momentarily disable the AIF when reconfiguring. That will glitch any running audio, making me wonder if the driver shouldn't be returning an error or at least complaining if it has to reconfigure instead. What's the use case where this might get triggered?
The case being fixed is like this:
aplay 48kHz.wav; aplay 96kHz.wav
The second open happens before pmdown_time so the AIF is still enabled. Writes to the AIF config registers only take effect if the AIF is disabled. Without this patch, the 96kHz.wav will play at 48kHz
If the glitch really matters, the driver can minimize by checking the change of sample rate and doing temporary turn on/off only when required.
Takashi