On Tuesday 24 September 2013 01:24 PM, Javier Martinez Canillas wrote: > On 09/24/2013 09:39 AM, Sricharan R wrote: >> Hi, >> On Monday 23 September 2013 10:37 PM, Tony Lindgren wrote: >>> * Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx> [130923 10:09]: >>>> On 09/23/2013 06:45 PM, Tony Lindgren wrote: >>>>> Hmm does this still work for legacy platform data based >>>>> drivers that are doing gpio_request() first? >>>>> >>>> Yes it still work when booting using board files. I tested on my OMAP3 board and >>>> it worked in both DT and legacy booting mode. >>> OK great. >>> >>>>> And what's the path for clearing things for PM when free_irq() >>>>> gets called? It seems that this would leave the GPIO bank >>>>> enabled causing a PM regression? >>>>> >>>> Indeed, I did set bank->mod_usage |= 1 << offset so the bank is enabled if the >>>> device goes to suspended and then resumed but I completely forget about the >>>> clearing path when the IRQ is freed. >>>> >>>> Which makes me think that we should probably maintain two usage variables, one >>>> for GPIO and another one for IRQ and check both of them on the suspend/resume pm >>>> functions. >>> Yes that it seems that they should be treated separately. >> To understand, why cant the flag be cleared in gpio_irq_shutdown ? > Hi Sricharan, > > Without this patch today drivers do this: > > gpio_request(gpio, "foo IRQ"); // bank->mod_usage |= 1 << offset > gpio_direction_input(gpio); > > and then request a IRQ with: > > irq = gpio_to_irq(gpio); > request_irq(irq, ...); > > later on its cleanup path: > > free_irq(irq, dev); > gpio_free(gpio) // bank->mod_usage &= ~(1 << offset); > > So if you clear the flag on gpio_irq_shutdown then bank module won't be enabled > after a suspend making drivers using the GPIO after freeing the IRQ to fail. > > So the idea is to have something like this: > > a) Drivers that request both the GPIO and IRQ > > gpio_request(gpio, "foo IRQ"); // bank->mod_usage |= 1 << offset > gpio_direction_input(gpio); > > irq = gpio_to_irq(gpio); > request_irq(irq, ...); // bank->irq_usage |= 1 << offset > > free_irq(irq, dev); // bank->irq_usage &= ~(1 << offset); > gpio_free(gpio) // bank->mod_usage &= ~(1 << offset); > > b) Drivers that just request the IRQ: > > irq = gpio_to_irq(gpio); > request_irq(irq, ...); // bank->irq_usage |= 1 << offset > free_irq(irq, dev); // bank->irq_usage &= ~(1 << offset); > > So irq_usage or mod_usage is set means that the bank has to be enabled and if > both are not set means that the bank module can be disabled. > Ok get it. Thanks. Regards, Sricharan -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
