From: Alexander Gordeev <agordeev@redhat.com>
Date: Mon, 29 Sep 2014 16:26:01 +0000 (+0200)
Subject: AHCI: Do not read HOST_IRQ_STAT reg in multi-MSI mode
X-Git-Tag: omap-for-v3.19/prcm-cleanup~133^2~4
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=227dfb4dbf109596d76a9b842856c4ff68e4efb2;p=pandora-kernel.git

AHCI: Do not read HOST_IRQ_STAT reg in multi-MSI mode

As described in AHCI v1.0 specification chapter 10.6.2.2
"Multiple MSI Based Messages" generation of interrupts
is not controlled through the HOST_IRQ_STAT register.

Considering MMIO access is expensive remove unnecessary
reading and writing of HOST_IRQ_STAT register.

Further, serializing access to the host data is no longer
needed and the interrupt service routine can avoid competing
on the host lock.

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Suggested-by: "Jiang, Dave" <dave.jiang@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "Jiang, Dave" <dave.jiang@intel.com>
Cc: linux-ide@vger.kernel.org
---

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