[alsa-devel] [PATCH] fm801: move to pcim_* and devm_* functions

[Andy Shevchenko]

On Tue, Jan 20, 2015 at 3:48 PM, Takashi Iwai <tiwai at suse.de> wrote:
> At Tue, 20 Jan 2015 15:46:13 +0200,
> Andy Shevchenko wrote:
>>
>> On Tue, Jan 20, 2015 at 2:42 PM, Takashi Iwai <tiwai at suse.de> wrote:
>> > At Wed, 07 Jan 2015 15:59:35 +0100,
>> > Takashi Iwai wrote:
>>
>> []
>>
>>
>> > I recalled finally why I didn't want this sort of changes.  Namely,
>> > devm_request_irq() can't be used safely for the shared PCI
>> > interrupts.
>> >
>> > There is a small open window between the driver's remove call
>> > (i.e. card's private_free or device free calls) and the call of
>> > devres_release_all().  The registered irq handler still remains during
>> > this window.  When an irq is triggered from another shared device
>> > during this, it goes to the remaining irq handler and accesses the
>> > hardware unexpectedly.  In the case of snd_fm801_interrupt(), it's not
>> > too bad, though.
>>
>> Don't we have interrupts disabled on ->remove() stage?
>
> It's a shared irq, so it doesn't help even if your device disables the
> irq.  The other device can trigger the irq line at any time.

Got it. We can call devm_free_irq() explicitly in the ->remove() then.

-- 
With Best Regards,
Andy Shevchenko