From mboxrd@z Thu Jan  1 00:00:00 1970
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
Subject: Re: [PATCH 15/20] ASoC: fsl: make fsl_ssi driver
	compilable on	ARM/IMX
Date: Mon, 5 Mar 2012 00:04:11 +0000
Message-ID: <20120305000411.GL7363@n2100.arm.linux.org.uk>
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To: Tabi Timur-B04825 <B04825@freescale.com>
Cc: "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>, Shawn Guo <shawn.guo@linaro.org>, Sascha Hauer <s.hauer@pengutronix.de>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Mark Brown <broonie@opensource.wolfsonmicro.com>
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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.