[PATCH v5 1/2] mfd: Add anatop mfd driver

Mark Brown broonie at opensource.wolfsonmicro.com
Thu Mar 1 11:30:32 UTC 2012

On Thu, Mar 01, 2012 at 05:10:51PM +0800, Ying-Chun Liu (PaulLiu) wrote:

> +	spin_lock(&adata->reglock);
> +	val = readl(adata->ioreg + addr);
> +	spin_unlock(&adata->reglock);

Do you really need to take a lock for a single read operation from a
memory mapped register?  I'd expect this to be atomic in itself.  You
need to lock on read/modify/write cycles to make sure that you don't get
a read/read/modify/modify/write/write and misplace one of the modifies
but that's not an issue for an isolated read.
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