summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2008-07-05 13:10:50 +0900
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-05 13:05:37 -0700
commitd28f87aa87ce8b196349d7c306a7e6fe3abd7155 (patch)
treec6bc6d198536772cd50d08c6772e291c5ba91f31
parentd79df630f622806c4d0e116fbaf6ebf6baf53461 (diff)
downloadlinux-sh-d28f87aa87ce8b196349d7c306a7e6fe3abd7155.tar.gz
ahci: give another shot at clearing all bits in irq_stat
Commit ea0c62f7cf70f13a67830471b613337bd0c9a62e tried to clear all bits in irq_stat but it didn't actually achieve that as irq_stat was anded with port_map right after read. This patch makes ahci driver always use the unmasked value to clear irq_status. While at it, add explanation on the peculiarities of ahci IRQ clearing. This was spotted by Linus Torvalds. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/ata/ahci.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 061817a3a0e5..5e6468a7ca4b 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1777,7 +1777,7 @@ static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
struct ahci_host_priv *hpriv;
unsigned int i, handled = 0;
void __iomem *mmio;
- u32 irq_stat;
+ u32 irq_stat, irq_masked;
VPRINTK("ENTER\n");
@@ -1786,16 +1786,17 @@ static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
/* sigh. 0xffffffff is a valid return from h/w */
irq_stat = readl(mmio + HOST_IRQ_STAT);
- irq_stat &= hpriv->port_map;
if (!irq_stat)
return IRQ_NONE;
+ irq_masked = irq_stat & hpriv->port_map;
+
spin_lock(&host->lock);
for (i = 0; i < host->n_ports; i++) {
struct ata_port *ap;
- if (!(irq_stat & (1 << i)))
+ if (!(irq_masked & (1 << i)))
continue;
ap = host->ports[i];
@@ -1812,6 +1813,15 @@ static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
handled = 1;
}
+ /* HOST_IRQ_STAT behaves as level triggered latch meaning that
+ * it should be cleared after all the port events are cleared;
+ * otherwise, it will raise a spurious interrupt after each
+ * valid one. Please read section 10.6.2 of ahci 1.1 for more
+ * information.
+ *
+ * Also, use the unmasked value to clear interrupt as spurious
+ * pending event on a dummy port might cause screaming IRQ.
+ */
writel(irq_stat, mmio + HOST_IRQ_STAT);
spin_unlock(&host->lock);