[alsa-devel] [PATCH] ASoC: Intel: bytcr_rt5640: fallback mechanism if MCLK is not enabled

[Mark Brown]

On Thu, Dec 15, 2016 at 08:42:22AM +0100, Takashi Iwai wrote:
> Pierre-Louis Bossart wrote:

> > >>  			dev_err(&pdev->dev,
> > >>  				"Failed to get MCLK from pmc_plt_clk_3: %ld\n",
> > >>  				PTR_ERR(priv->mclk));
> > >> -			return PTR_ERR(priv->mclk);
> > >> +
> > >> +			/* Fall back to bitclock only */
> > >> +			byt_rt5640_quirk &= ~BYT_RT5640_MCLK_EN;

> > > This is broken for probe deferral, I'd expect this to be explicitly
> > > checking for a no clock mapped error code (probably -ENOENT) rather than
> > > just ignoring all errors.

> > I don't understand the probe deferral concept here. Are you saying
> > fall back to the bit clock mode if the status is -ENOENT and fail
> > otherwise?

> The clk driver may return -EPROBE_DEFER, and in that case, the intel
> driver should also defer the probe as well.  Or, like -ENOMEM, it
> indicates a serious error, and then better bail out.

> So, we need to figure out which error code should fall back to the
> legacy mode.  (Or vice versa, which error code shouldn't be ignored.)

Exactly.  -ENOENT is what other subsystems return, I've not specifically
checked the clock API.
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