Re: [PATCH v3 1/1] input: add support for Nomadik SKE keypad controller

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

On Wed, Sep 08, 2010 at 04:19:45PM +0200, Linus Walleij wrote:
> 2010/9/8 Trilok Soni <tsoni@codeaurora.org>:
> > [Sundar]
> >> Yes it can. I am seeing increasing tendency to migrate to threaded_irq from the legacy irq recently
> >> and hence the threaded request.
> >
> > Use threaded_irq only when needed with different flags and not everywhere. In this case we don't
> > need threaded irq at all.
> 
> Look closer at the IRQ handler:
> 
> +static irqreturn_t ske_keypad_irq(int irq, void *dev_id)
> (...)
> +       /*
> +        * if KPASON is not ready, we cannot read data registers
> +        * so wait for a debounce period; if still not settled,
> +        * we fire a timer and exit the IRQ
> +        */
> +       while ((readl(keypad->reg_base + SKE_CR) & SKE_KPASON) && timeout--)
> +               cpu_relax();
> 
> Active polling. Surely you want this to be preemptible? Thus ->
> threaded handler.
> 

Actually I'd like that form of active polling not be there at all.

-- 
Dmitry