Hi Arnd, On 24.07.2012 14:56, Arnd Bergmann wrote: > On Monday 23 July 2012, Daniel Mack wrote: >> (Cc: Arnd) >> >> On 22.07.2012 19:10, Daniel Mack wrote: >>> of_gpio_simple_xlate() is called for each chip when a GPIO is looked up. >>> When registering several chips off the same DT node (with different pin >>> offsets) however, the lookup fails as the GPIO number passed in to >>> of_gpio_simple_xlate() is likely higher than the chip's ->ngpio value. >>> >>> Fix that by taking into account the chip's ->base value, and return the >>> relative offset of the pin inside the chip. >>> >>> Signed-off-by: Daniel Mack <zon...@gmail.com> >>> Cc: Grant Likely <grant.lik...@secretlab.ca> >>> Cc: Linus Walleij <linus.wall...@stericsson.com> >>> --- >>> >>> I'm currently porting the PXA pieces over to DT, and stumbled over what >>> looks like an obvious bug to me. Correct me if I'm mistaken, but I see >>> no reason why one shouldn't be able to instanciate several GPIO chips >>> from a single DT node. > > But why would you do that? Both the "gpiochip" and its DT representation > attempt to represent the hardware structure. If they don't match, then > I'd assume one of them is wrong ;-)
Well, have a look at what's currently there in drivers/gpio/gpio-pxa.c. There are several gpio_chips that are registered. On the DT side, however, I would much like to present all GPIO line in one array, so the numbers match the hardware documentation. I prepared patches for all that and they work find, the only thing I need to touch in the core for that is this minor detail. > >>> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c >>> index d18068a..51bc232 100644 >>> --- a/drivers/gpio/gpiolib-of.c >>> +++ b/drivers/gpio/gpiolib-of.c >>> @@ -147,13 +147,13 @@ int of_gpio_simple_xlate(struct gpio_chip *gc, >>> if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells)) >>> return -EINVAL; >>> >>> - if (gpiospec->args[0] >= gc->ngpio) >>> + if (gpiospec->args[0] >= gc->ngpio + gc->base) >>> return -EINVAL; >>> >>> if (flags) >>> *flags = gpiospec->args[1]; >>> >>> - return gpiospec->args[0]; >>> + return gpiospec->args[0] - gc->base; >>> } >>> EXPORT_SYMBOL(of_gpio_simple_xlate); > > Where would that gc->base come from? It is set up when the chips are initialized. Let's put it that way: why would we have this ->base if it is practically unusable in devicetree environments? And In case ->base equals 0, this patch is a no-op anyway. Thanks, Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
