Re: [PATCH] mmc: sdhci: disable irq in sdhci host suspend ranther than free this irq
From: Thomas Gleixner
Date: Thu Jan 28 2016 - 11:22:54 EST
On Thu, 28 Jan 2016, Ulf Hansson wrote:
> On 28 January 2016 at 11:20, Russell King - ARM Linux
> <linux@xxxxxxxxxxxxxxxx> wrote:
> >> - free_irq(host->irq, host);
> >> + disable_irq(host->irq);
> > This is really not acceptable I'm afraid. While it's common on ARM for
> > each interrupt to be uniquely allocated to a peripheral, not all SDHCI
> > platforms have that luxury.
> > SDHCI is also used on PCI, and on x86 platforms, it's common to have PCI
> > interrupts shared between (sometimes many) different PCI devices.
> > For example, on my laptop:
> > 18: 1089806 286185 IO-APIC-fasteoi uhci_hcd:usb8, r852, mmc0
> > the SDHCI interrupt is shared with two other peripherals - one USB
> > controller and a NAND device.
> > Disabling the interrupt will adversely impact other peripherals and
> > cause regressions where the interrupt is shared.
> I thought disable|enable_irq() was being reference counted, so it
> shouldn't impact the other peripherals for shared IRQs. I might have
> understood this wrong though!?
It's reference counted. But it disables the irq line and not a particular
> Although, as if that's the case it also means that the IRQ can still
> reach sdhci's irq handler as it hasn't actually been disabled.
No. The result is that the other devices on the same irq line won't get any
> Therefore, the only way we currently can make sure to don't get the
> IRQ is to free and later re-request it. Now, apparently that has
> issues when using threaded IRQ handlers.
What's the issue?