On Wed, Nov 11, 2009 at 06:08:49PM +0100, ext Dmitry Torokhov wrote:
> On Wed, Nov 11, 2009 at 04:52:06PM +0200, Mika Westerberg wrote:
> > On Wed, Nov 11, 2009 at 03:37:38PM +0100, ext Ferenc Wagner wrote:
> > > Mika Westerberg <ext-mika.1.westerberg@xxxxxxxxx> writes:
> > >
> > > > + for (i = 0; i < pdata->nbuttons; i++) {
> > > > + struct gpio_keys_button *button = &pdata->buttons[i];
> > > > + struct gpio_button_data *bdata = &ddata->data[i];
> > > > +
> > > > + if (button->code == st->code && button->type == st->type) {
> > > > + switch (st->state) {
> > > > + case EVENT_STATE_DISABLE:
> > > > + if (bdata->state == EVENT_STATE_ENABLE) {
> > > > + bdata->state = EVENT_STATE_DISABLE;
> > > > + /*
> > > > + * Disable physical irq line. This is
> > > > + * enough also for keeping device from
> > > > + * waking up during sleep so no need
> > > > + * to change wakeup flags for this irq.
> > > > + */
> > > > + disable_irq(gpio_to_irq(button->gpio));
> > >
> > > Hi Mika,
> > >
> > > Did you consider what would happen when several GPIO buttons share a
> > > single IRQ? The current code does not support this (it uses IRQF_SHARED
> > > for a different reason), but this is very much possible: see for example
> > > http://thread.gmane.org/gmane.linux.kernel.input/8775 for a related
> > > thread which unfortunately died off without conclusion (but the patch
> > > went in).
> >
> > Good point! I didn't consider that at all.
> >
> > Maybe we disable irq only when it is not shared with anything else (even
> > with other GPIO button) and otherwise return -EINVAL or something like
> > that?
> >
>
> How could a driver know if it is [going to] share irq with another
> driver. Dmitry's (the other one ;) ) patch was needed because he wanted
> to share IRQ with another device entirely.
Ah, it seems that there is no such API in the kernel :(
How about specifying whether some GPIO button allows sharing of the IRQ
in board files (e.g amend gpio_keys_button struct)? Then we can disable
only those GPIO buttons where IRQ line is not shared.
Thanks,
MW
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