AHCI: Do not read HOST_IRQ_STAT reg in multi-MSI mode
authorAlexander Gordeev <agordeev@redhat.com>
Mon, 29 Sep 2014 16:26:01 +0000 (18:26 +0200)
committerTejun Heo <tj@kernel.org>
Mon, 6 Oct 2014 15:43:36 +0000 (11:43 -0400)
commit227dfb4dbf109596d76a9b842856c4ff68e4efb2
tree21d347c6ee2f4d53fffd158bab63acecd23d9a39
parent5ee1cfd975518bc9cdcd79e0b76552b5ae5c8c1e
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
drivers/ata/ahci.h
drivers/ata/libahci.c