On Wed, Jul 2, 2014 at 4:54 AM, Nick Dyer <nick.dyer@xxxxxxxxxxx> wrote: > On 02/07/14 11:49, Sekhar Nori wrote: >> On Tuesday 01 July 2014 09:44 PM, Stephen Warren wrote: >>> On the Tegra systems I have, IRQF_TRIGGER_FALLING is the correct (or at >>> least a valid) choice. That's probably because the Atmel IRQ signal is >>> routed to our GPIO controller, which is also an IRQ controller, and then >>> "forwarded" up the chain to the GIC, with the polarity the GIC expects. >>> >>> If IRQ_TRIGGER_FALLING doesn't work everywhere, then we'll need to add >>> some kind of DT property to configure the polarity of the IRQ output. >> >> Yeah, I think so too. >> >> Nick, >> >> If you are going to rebase your branch, will you be able to fold in the >> patch in my previous e-mail? Else, I can send a more formal patch to you. > > Either IRQF_TRIGGER_FALLING or IRQF_TRIGGER_LOW will work with these chips > (it isn't a question of polarity but whether it's edge- or level- > triggered). There isn't a sensible default. Atmel prefer IRQF_TRIGGER_LOW, > however I've seen some IRQ controllers will revert to a polled mode for > IRQF_TRIGGER_LOW, which kills performance. > > So, the sensible course of action seems to be to remove the default > IRQF_TRIGGER_FALLING in the device tree parsing, and provide a device tree > parameter for the flags. If you agree, I will sort this out at my end, you > don't need to send a patch. > > I have to leave it in in the case where there is neither static platform > data, or device tree node, because that is used for some systems, but that > shouldn't affect either of you. In this case board code should take care of setting up the interrupt properly and the driver should simply use 0 as flags in request_irq(). By the way, doesn't generic DT infrastructure already allow specifying interrupt triggers and sets them up properly? Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
