Re: [PATCH] input: add support for PowerOn(PonKey) button on the AB8500 MFD

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Trilok,

On Fri, Sep 03, 2010 at 01:23:55AM +0530, Trilok Soni wrote:
> Hi Dmitry,
> 
> On 9/2/2010 10:52 PM, Dmitry Torokhov wrote:
> > 
> >>>
> >>> I'll change it to use normal interrupts locally, no need to resubmit.
> >>
> >> Changing it to request_irq() will cause it to fail, because __setup_irq
> >> will error out if this is a nested thread interrupt and no interrupt
> >> thread is specified.  request_any_context_irq() should work, if you
> >> would like to get rid of explicitly asking for a threaded irq.
> >>
> > 
> > OK, request_any_context_irq() it is then.
> 
> Though request_any_context_irq() would work here, but I would still
> prefer to use the request_threaded_irq(..) because power-on key functionality
> is in-built to this PMIC chip and it will always be threaded it seems. No new
> thread will be created because they did the right thing in their PMIC core
> irq code it seems.
> 
> We could prefer the request_any_context_irq(...) when we are using the line
> (say gpio) coming out of this PMIC and used by generic device driver where
> the another h/w design could have memory mapped gpio for the same device driver.
> 
> Better to keep this driver with request_threaded_irq(..) only.
> 

I disagree. I believe that drivers should use request_threaded_irq()
only if they _themselves_ require handling interrupts in process context.
The fact that someone up the stack set up threaded IRQ and not hard IRQ
should not matter.

Ideally I'd love request_irq() to be what request_any_context_irq()
currently is and then we'd have request_hard_irq() for driver that
absolutely need hard IRQ context.

Thanks.

-- 
Dmitry