On Thu, Nov 15, 2018 at 01:25:28PM +0200, Dimitris Papavasiliou wrote: > Unless I misunderstand, I can't change the CODEC driver's settings > (such as ignore_pmdown_time) from the machine driver. Even if I You can get to the CODEC driver from the machine driver, and for idle_bias_off there's probably a good case for just setting it unconditionally given the lack of delays. > could, I'm not entirely sure it would consistently fix the problem. > For instance, if the auto-mute is set to 21ms, the DAC output is muted > automatically by the chip after 21ms of no input and the pop still > manages to get through before that on occasion. That's why I'm suggesting ignore_pmdown_time as a first thing to try - it should cause the powerdown to happen synchronously so there's no chance for anything else to go in and change the clocking to cause a pop. > It also seems like a roundabout solution, that depends on proper > sequencing, i.e. it is assumed that the device is always biased > off before the hw_params callback of the machine driver is > called, something which might change in the future and cause a > regression. The whole goal with the combination of idle_bias_off and ignore_pmdown_time is to ensure that this happens in an orderly fashion in a way that the core knows about. > afterwards. Isn't there some way to lock the component/CODEC's > regmap, so as to perform an operation involving more than one > register change atomically? Something like > snd_soc_component_lock/unlock_regmap sounds like it might be > generally useful, to synchronize access to a chip's registers > across CODE/machine/etc. drivers. No, there's no facility for that and it's such a niche case that I'm not convinced it's a good idea to do it. Another thing you could do here though is to do the bounce as part of set_sysclk() in the CODEC driver.
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