[alsa-devel] [PATCH 15/20] ASoC: fsl: make fsl_ssi driver compilable on ARM/IMX

[Russell King - ARM Linux]

On Sun, Mar 04, 2012 at 11:32:50PM +0000, Tabi Timur-B04825 wrote:
> Russell King - ARM Linux wrote:
> > Is the SCR shared between capture and playback?  In that case, what
> > makes this read-modify-write thread safe?
> 
> What's "SCR"?

I assumed you knew the code you were commenting on.

                clrbits32(&ssi->scr, CCSR_SSI_SCR_SSIEN);

The register these functions seem to be used on appears to be called
'SCR'.

> It's not thread-safe on PPC, but then neither is the entire function.  You 
> can't have two threads attempt to initialize the hardware at the same 
> time.

Why do you say "can't" - what prevents it?  If nothing, then this stuff
is buggy when preempt is enabled, or you're running on SMP.