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
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 6a22055..40f0e34 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -304,7 +304,7 @@
unsigned int ncq_saw_d2h:1;
unsigned int ncq_saw_dmas:1;
unsigned int ncq_saw_sdb:1;
- u32 intr_status; /* interrupts to handle */
+ atomic_t intr_status; /* interrupts to handle */
spinlock_t lock; /* protects parent ata_port */
u32 intr_mask; /* interrupts to enable */
bool fbs_supported; /* set iff FBS is supported */