Commit 2cf532f5 authored Apr 17, 2014 by Alexander Gordeev Committed by Tejun Heo Apr 18, 2014

ahci: Do not receive interrupts sent by dummy ports



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: 5ca72c4f ("AHCI: Support multiple MSIs")

parent ccf8f53c

drivers/ata/ahci.c

+10 −6

Original line number	Original line	Diff line number	Diff line
	@@ -1241,10 +1241,14 @@ int ahci_host_activate(struct ata_host *host, int irq, unsigned int n_msis)
	for (i = 0; i < host->n_ports; i++) {		for (i = 0; i < host->n_ports; i++) {
	struct ahci_port_priv *pp = host->ports[i]->private_data;		struct ahci_port_priv *pp = host->ports[i]->private_data;

	/* pp is NULL for dummy ports */		/* Do not receive interrupts sent by dummy ports */
	if (pp)		if (!pp) {
	rc = devm_request_threaded_irq(host->dev,		disable_irq(irq + i);
	irq + i, ahci_hw_interrupt,		continue;
			}

			rc = devm_request_threaded_irq(host->dev, irq + i,
			ahci_hw_interrupt,
	ahci_thread_fn, IRQF_SHARED,		ahci_thread_fn, IRQF_SHARED,
	pp->irq_desc, host->ports[i]);		pp->irq_desc, host->ports[i]);
	if (rc)		if (rc)

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