On 07/31/2013 03:35 AM, Javier Martinez Canillas wrote: > On 07/31/2013 01:44 AM, Linus Walleij wrote: >> On Tue, Jul 30, 2013 at 6:30 AM, Grant Likely <grant.likely@xxxxxxxxxx> wrote: >>> On Mon, Jul 29, 2013 at 6:36 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: >>>> To solve this dilemma, perform an interrupt consistency check >>>> when adding a GPIO chip: if the chip is both gpio-controller and >>>> interrupt-controller, walk all children of the device tree, >>>> check if these in turn reference the interrupt-controller, and >>>> if they do, loop over the interrupts used by that child and >>>> perform gpio_reques() and gpio_direction_input() on these, >>>> making them unreachable from the GPIO side. >>> >>> Ugh, that's pretty awful, and it doesn't actually solve the root >>> problem of the GPIO and IRQ subsystems not cooperating. It's also a >>> very DT-centric solution even though we're going to see the exact same >>> issue on ACPI machines. >> >> The problem is that the patches for OMAP that I applied >> and now have had to revert solves it in an even uglier way, >> leading to breaking boards, as was noticed. >> >> The approach in this patch has the potential to actually >> work without regressing a bunch of boards... >> >> Whether this is a problem in ACPI or not remains to be seen, >> but I'm not sure about that. Device trees allows for a GPIO line >> to be used as an interrupt source and GPIO line orthogonally, >> and that is the root of this problem. Does ACPI have the same >> problem, or does it impose natural restrictions on such use >> cases? >> > > I agree with Linus here. The problem is that GPIO controllers that can work as > IRQ sources are treated in the kernel as if there where two separate controlers > that are rather orthogonal: an irq_chip and a gpio_chip. > But DT allows to use a GPIO line as an IRQ just by using an omap-gpio phandle as > "interrupt-parent". > > So, there should be a place where both irq_chip and gpio_chip has to be related > somehow to properly configure a GPIO (request it and setting it as input) when > used as an IRQ by DT. > > My patch for OMAP used an irq_domain_ops .map function handler to configure the > GPIO when a IRQ was mapped since that seemed to me as the best place to do it. > This worked well in OMAP2+ platforms but unfortunately broke OMAP1 platforms > since they are still using legacy domain mapping thus not call .map. Just wondering- why .map not called for omap1? irq_create_mapping does seem to call -> irq_domain_associate which calls map function. For omap case, GPIO driver does call irq_create_mapping, just like omap2+ no? Further, if for any reason the .map is not called. Can you not call gpio_request yourself direct in omap_gpio_chip_init function? Does it really matter if you call gpio_request from .map or from the chip_init function? Also on a different note.. this would call gpio_request for *every* gpio line, but isn't that what your original patch that got reverted was doing in omap_gpio_chip_init: + if (!bank->chip.of_node) + for (j = 0; j < bank->width; j++) + irq_create_mapping(bank->domain, j); Just trying to understand your initial patch better. Regards, -Joel -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
