[alsa-devel] [PATCH v2] ASoC: sgtl5000: defer the probe if clock is not found

[Mark Brown]

On Tue, Jul 16, 2013 at 09:17:27AM +0800, Shawn Guo wrote:

> It fixes the regression on imx28 since commit 9e13f34 (ASoC: sgtl5000:
> Let the codec acquire its clock).

Looking at the code the race has always been there, the same issue
exists in the old code in the machine driver.  But I guess there may
have been some (surprising given that we now wait for an I2C device to
be registered) reordering.

> I'm still not going to fix this regression during -rc at clock core
> level with the risk of breaking clock API users and being yelled by
> clock maintainer.

I'd be much happier with this if there were at least some effort being
made to discuss the issue at a generic level.  If we were adding a new
API for deferring clocks (which was the suggestion) then there'd be no
risk to existing users...

> +		/* Defer the probe to see if the clk will be provided later */
> +		if (ret == -ENOENT)
> +			return -EPROBE_DEFER;

What's magic about -ENOENT here?
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