diff options
| author | Tejun Heo <tj@kernel.org> | 2008-07-05 13:10:50 +0900 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-05 13:05:37 -0700 |
| commit | d28f87aa87ce8b196349d7c306a7e6fe3abd7155 (patch) | |
| tree | c6bc6d198536772cd50d08c6772e291c5ba91f31 /drivers/ata | |
| parent | d79df630f622806c4d0e116fbaf6ebf6baf53461 (diff) | |
| download | lwn-d28f87aa87ce8b196349d7c306a7e6fe3abd7155.tar.gz lwn-d28f87aa87ce8b196349d7c306a7e6fe3abd7155.zip | |
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>
Diffstat (limited to 'drivers/ata')
| -rw-r--r-- | drivers/ata/ahci.c | 16 |
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); |