[alsa-devel] [PATCH v4 5/7] ASoC: intel - add Skylake HDA audio driver

[Mark Brown]

On Tue, Jun 02, 2015 at 12:48:50PM +0200, Takashi Iwai wrote:
> Mark Brown wrote:

> > Why does the driver care though?  IRQF_SHARED is advertising the
> > capabilities of the hander, not a requirement on the hardware - if the
> > interrupt physically can't be shared then the ability to share it will
> > never get used but that shouldn't matter.

> Because the kernel doesn't guarantee the exclusiveness of irq handler
> registration as long as you pass IRQF_SHARED.  That is, if we keep
> IRQF_SHARED and another driver tries to request_irq() for the same irq
> with again IRQF_SHARED.  But this shouldn't happen with MSI.

Sure, but how could that happen (given that the interrupt physically
can't be shared) and surely individual client drivers are the wrong
place to do this - it's not like MSI is the only interrupt type that has
trouble with sharability, if this is an issue we need to have checks and
enforcement for I'd expect the interrupt controller to be flagging
itself as unsharable.
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