From 227dfb4dbf109596d76a9b842856c4ff68e4efb2 Mon Sep 17 00:00:00 2001
From: Alexander Gordeev <agordeev@redhat.com>
Date: Mon, 29 Sep 2014 18:26:01 +0200
Subject: [PATCH] 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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