From: Will Deacon <will.deacon@arm.com>
Date: Mon, 14 Nov 2011 16:24:58 +0000 (+0100)
Subject: ARM: 7161/1: errata: no automatic store buffer drain
X-Git-Tag: v3.2-rc4~2^2~16
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=11ed0ba1754841316d4095478944300acf19acc3;p=pandora-kernel.git

ARM: 7161/1: errata: no automatic store buffer drain

This patch implements a workaround for PL310 erratum 769419. On
revisions of the PL310 prior to r3p2, the Store Buffer does not
automatically drain. This can cause normal, non-cacheable writes to be
retained when the memory system is idle, leading to suboptimal I/O
performance for drivers using coherent DMA.

This patch adds an optional wmb() call to the cpu_idle loop. On systems
with an outer cache, this causes an explicit flush of the store buffer.

Cc: stable@vger.kernel.org
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

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