From mboxrd@z Thu Jan 1 00:00:00 1970 From: broonie@opensource.wolfsonmicro.com (Mark Brown) Date: Thu, 1 Mar 2012 11:30:32 +0000 Subject: [PATCH v5 1/2] mfd: Add anatop mfd driver In-Reply-To: <1330593052-15184-1-git-send-email-paul.liu@linaro.org> References: <1330593052-15184-1-git-send-email-paul.liu@linaro.org> Message-ID: <20120301113031.GD3124@opensource.wolfsonmicro.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 836 bytes Desc: Digital signature URL: