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ahci: Do not receive interrupts sent by dummy ports

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In multiple MSI mode all AHCI ports (including dummy) get assigned
separate MSI vectors and (as result of execution
pci_enable_msi_exact() function) separate IRQ numbers, (mapped to the
MSI vectors).

Therefore, although interrupts from dummy ports are not desired they
are still enabled. We do not request IRQs for dummy ports, but that
only means we do not assign AHCI-specific ISRs to corresponding IRQ
numbers.

As result, dummy port interrupts still could come and traverse all the
way from the PCI device to the kernel, causing unnecessary overhead.

This update disables IRQs for dummy ports and prevents the described
issue.

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Tested-by: David Milburn <dmilburn@redhat.com>
Cc: linux-ide@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: 5ca72c4f7c ("AHCI: Support multiple MSIs")
This commit is contained in:
Alexander Gordeev 2014-04-17 18:06:15 +02:00 committed by Tejun Heo
parent ccf8f53cac
commit 2cf532f5e6
1 changed files with 10 additions and 6 deletions
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16
drivers/ata/ahci.c
View file

@ -1241,12 +1241,16 @@ int ahci_host_activate(struct ata_host *host, int irq, unsigned int n_msis)
for (i = 0; i < host->n_ports; i++) {
struct ahci_port_priv *pp = host->ports[i]->private_data;
/* pp is NULL for dummy ports */
if (pp)
rc = devm_request_threaded_irq(host->dev,
irq + i, ahci_hw_interrupt,
ahci_thread_fn, IRQF_SHARED,
pp->irq_desc, host->ports[i]);
/* Do not receive interrupts sent by dummy ports */
if (!pp) {
disable_irq(irq + i);
continue;
}
rc = devm_request_threaded_irq(host->dev, irq + i,
ahci_hw_interrupt,
ahci_thread_fn, IRQF_SHARED,
pp->irq_desc, host->ports[i]);
if (rc)
goto out_free_irqs;
}