Looping in DT people.
Please send subsequent patches also to devicetree@xxxxxxxxxxxxxxx
On Tue, Jun 14, 2016 at 8:57 PM, Uwe Kleine-König
<u.kleine-koenig@xxxxxxxxxxxxxx> wrote:
> Traditionally the n-th gpio device probed by the omap gpio driver got
> the gpio number range [n*32 .. n*32+31].
> When order of the devices probed by the driver changes (which can happen
> already now when some devices have a pinctrl and so the first probe
> attempt returns -ENODEV) the numbering changes.
>
> To ensure a deterministical numbering use of_alias_get_id to determine
> the base for a given device. If no respective alias exists fall back to
> the traditional numbering.
>
> For the unusual case where only a part of the gpio devices have a
> matching alias some of them might fail to probe. But if none of them has
> an alias or all, there is no conflict which should be good enough to
> maintain backward compatibility.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> ---
> drivers/gpio/gpio-omap.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> index b98ede78c9d8..4d91792e7266 100644
> --- a/drivers/gpio/gpio-omap.c
> +++ b/drivers/gpio/gpio-omap.c
> @@ -1053,9 +1053,26 @@ static int omap_gpio_chip_init(struct gpio_bank *bank, struct irq_chip *irqc)
> bank->chip.parent = &omap_mpuio_device.dev;
> bank->chip.base = OMAP_MPUIO(0);
> } else {
> + int gpio_alias_id __maybe_unused;
> +
> bank->chip.label = "gpio";
> - bank->chip.base = gpio;
> +
> +#if defined(CONFIG_OF_GPIO)
> + /*
> + * Traditionally the base is given out in first-come-first-serve
> + * order. This might shuffle the numbering of gpios if the
> + * probe order changes. So make the base deterministical if the
> + * device tree specifies alias ids.
> + */
> + gpio_alias_id = of_alias_get_id(bank->chip.of_node, "gpio");
> + if (gpio_alias_id >= 0)
> + bank->chip.base = bank->width * gpio_alias_id;
> + else
> +#endif
> + bank->chip.base = gpio;
> }
> +
> +
I need:
- A hunk of the patch to hit
Documentation/devicetree/bindings/gpio/gpio.txt
and describe the alias usage there
- an ACK from a DT bindings maintainer for this.
Yours,
Linus Walleij
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