[alsa-devel] [PATCH 1/2] ASoC: rt5670: Revert Keep sysclk on patch

[Bard Liao]

> -----Original Message-----
> From: Mark Brown [mailto:broonie at kernel.org]
> Sent: Monday, March 09, 2015 8:20 PM
> To: Bard Liao
> Cc: lgirdwood at gmail.com; alsa-devel at alsa-project.org; lars at metafoo.de;
> Flove; Oder Chiou; John Lin; mengdong.lin at intel.com; yao.jin at intel.com
> Subject: Re: [PATCH 1/2] ASoC: rt5670: Revert Keep sysclk on patch
> 
> On Mon, Mar 09, 2015 at 12:13:04PM +0000, Bard Liao wrote:
> 
> > System clock is needed for rt5670 jack detection function. Usually,
> > the system clock source is from MCLK. But some platform such as
> > Intel BSW will turn off MCLK in idle mode. So rt5670 need to switch the
> > system clock source to its internal clock. The action is done by machine
> > driver.
> 
> OK...  but if this is the case why does your patch not update any
> machine drivers?

The sysclk source switching is already in cht_bsw_rt5672.c.
But it switches to internal clock only but doesn't switch
back to PLL. Jin Yao will send a patch to fix it.

> 
> > There is a PLL power in rt5670. It should be on if we want to use
> > PLL as the system clock source. So we call force enable/disable pin
> > in rt5670_set_dai_sysclk. However, cht_bsw_rt5672.c call
> > snd_soc_dai_set_sysclk in platform_clock_control which is the dapm
> > event of "Platform Clock" widget. In that case,
> > snd_soc_dapm_disable_pin and snd_soc_dapm_sync are called
> > within a dapm event. I think it is not valid.
> 
> This is very unusual, normally such system clock reconfiguration would
> be done in the set_bias_level() callback not in a DAPM event.  Doing it
> in a DAPM event sounds unreliable as there are only weak guarantees
> about the state of the system.

> 
> ------Please consider the environment before printing this e-mail.