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authorTejun Heo <tj@kernel.org>2008-07-05 00:10:50 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-05 16:05:37 -0400
commitd28f87aa87ce8b196349d7c306a7e6fe3abd7155 (patch)
treec6bc6d198536772cd50d08c6772e291c5ba91f31 /drivers/ata
parentd79df630f622806c4d0e116fbaf6ebf6baf53461 (diff)
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.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)
1777 struct ahci_host_priv *hpriv; 1777 struct ahci_host_priv *hpriv;
1778 unsigned int i, handled = 0; 1778 unsigned int i, handled = 0;
1779 void __iomem *mmio; 1779 void __iomem *mmio;
1780 u32 irq_stat; 1780 u32 irq_stat, irq_masked;
1781 1781
1782 VPRINTK("ENTER\n"); 1782 VPRINTK("ENTER\n");
1783 1783
@@ -1786,16 +1786,17 @@ static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
1786 1786
1787 /* sigh. 0xffffffff is a valid return from h/w */ 1787 /* sigh. 0xffffffff is a valid return from h/w */
1788 irq_stat = readl(mmio + HOST_IRQ_STAT); 1788 irq_stat = readl(mmio + HOST_IRQ_STAT);
1789 irq_stat &= hpriv->port_map;
1790 if (!irq_stat) 1789 if (!irq_stat)
1791 return IRQ_NONE; 1790 return IRQ_NONE;
1792 1791
1792 irq_masked = irq_stat & hpriv->port_map;
1793
1793 spin_lock(&host->lock); 1794 spin_lock(&host->lock);
1794 1795
1795 for (i = 0; i < host->n_ports; i++) { 1796 for (i = 0; i < host->n_ports; i++) {
1796 struct ata_port *ap; 1797 struct ata_port *ap;
1797 1798
1798 if (!(irq_stat & (1 << i))) 1799 if (!(irq_masked & (1 << i)))
1799 continue; 1800 continue;
1800 1801
1801 ap = host->ports[i]; 1802 ap = host->ports[i];
@@ -1812,6 +1813,15 @@ static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
1812 handled = 1; 1813 handled = 1;
1813 } 1814 }
1814 1815
1816 /* HOST_IRQ_STAT behaves as level triggered latch meaning that
1817 * it should be cleared after all the port events are cleared;
1818 * otherwise, it will raise a spurious interrupt after each
1819 * valid one. Please read section 10.6.2 of ahci 1.1 for more
1820 * information.
1821 *
1822 * Also, use the unmasked value to clear interrupt as spurious
1823 * pending event on a dummy port might cause screaming IRQ.
1824 */
1815 writel(irq_stat, mmio + HOST_IRQ_STAT); 1825 writel(irq_stat, mmio + HOST_IRQ_STAT);
1816 1826
1817 spin_unlock(&host->lock); 1827 spin_unlock(&host->lock);