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ahci: give another shot at clearing all bits in irq_stat
Commit ea0c62f7cf
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>
This commit is contained in:
parent
d79df630f6
commit
d28f87aa87
1 changed files with 13 additions and 3 deletions
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@ -1777,7 +1777,7 @@ static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
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struct ahci_host_priv *hpriv;
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unsigned int i, handled = 0;
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void __iomem *mmio;
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u32 irq_stat;
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u32 irq_stat, irq_masked;
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VPRINTK("ENTER\n");
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@ -1786,16 +1786,17 @@ static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
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/* sigh. 0xffffffff is a valid return from h/w */
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irq_stat = readl(mmio + HOST_IRQ_STAT);
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irq_stat &= hpriv->port_map;
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if (!irq_stat)
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return IRQ_NONE;
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irq_masked = irq_stat & hpriv->port_map;
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spin_lock(&host->lock);
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for (i = 0; i < host->n_ports; i++) {
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struct ata_port *ap;
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if (!(irq_stat & (1 << i)))
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if (!(irq_masked & (1 << i)))
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continue;
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ap = host->ports[i];
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@ -1812,6 +1813,15 @@ static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
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handled = 1;
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}
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/* HOST_IRQ_STAT behaves as level triggered latch meaning that
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* it should be cleared after all the port events are cleared;
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* otherwise, it will raise a spurious interrupt after each
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* valid one. Please read section 10.6.2 of ahci 1.1 for more
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* information.
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*
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* Also, use the unmasked value to clear interrupt as spurious
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* pending event on a dummy port might cause screaming IRQ.
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*/
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writel(irq_stat, mmio + HOST_IRQ_STAT);
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spin_unlock(&host->lock);
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