request an irq without enabling? [Was: Re: [PATCH] gpio: mxs: implement get_direction callback]

Uwe Kleine-König u.kleine-koenig at
Mon Nov 17 01:51:54 PST 2014


Sorry for the just sent unfinished mail. I pressed "send" instead of
"reedit" after adding tglx to the recipients. Apart from the topic
handled in this mail it's complete though.

On Mon, Nov 17, 2014 at 10:11:25AM +0100, Janusz Użycki wrote:
> W dniu 2014-11-17 o 09:28, Uwe Kleine-König pisze:
> >I think mctrl_gpio_init should request the needed irqs, but not enable
> >them. Not sure there is a corresponding request_irq variant for that.
> What would you propose?
Thomas: Is there something available among the irq functions for that.
The use case is that when probing an uart driver the modem control irqs
should only be enabled when the enable_ms callback is called by the
tty/serial framework. So we'd like to have something like
request_irq_noenable. This way the enable_ms callback would just need
to call enable_irq without first checking if the handler is already

The less nice alternatives are:

 - use request_irq(..); disable_irq(); and handle the short window where
   irqs are on but not yet desired.
 - only request_irq in the enable_ms callback, and free_irq in

Any ideas?

Best regards

Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 |  |

More information about the linux-arm-kernel mailing list