On Sat, 10 Jun 2017 21:58:41 +0300
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> While using GPIO library API we might get into troubles in the future,
> because we can't rely on label name in the driver since vendor firmware
> might provide any GPIO pin there, e.g. "reset", and even mark it in _DSD
> (in which case the request will fail).
>
> To avoid inconsistency and potential issues we have two options:
> a) generate GPIO ACPI mapping table and supply it via
> acpi_dev_add_driver_gpios(), or
> b) just pass NULL as connection ID.
>
> The b) approach is much simpler and would work since the driver relies
> on GPIO indices only. Moreover, the _CRS fallback mechanism, when
> requesting GPIO, is going to be stricter, and supplying non-NULL
> connection ID when neither _DSD, nor GPIO ACPI mapping is present, will
> make request fail.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Hi Andy,
A bit of googling suggests that this is one of a number of similar patches.
I'd have appreciated some cross references in here as otherwise it seems
to have come out of nowhere.
Also, I'd be happier with an Ack from Linus Walleij on a change like
this to confirm the method (a reference to him saying it was fine
elsewhere would be fine as well!)
Anyhow I've cc'd Linus in the meantime.
Thanks,
Jonathan
> ---
> drivers/iio/accel/mma9551.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/iio/accel/mma9551.c b/drivers/iio/accel/mma9551.c
> index bf2704435629..1f53f08476f5 100644
> --- a/drivers/iio/accel/mma9551.c
> +++ b/drivers/iio/accel/mma9551.c
> @@ -27,7 +27,6 @@
>
> #define MMA9551_DRV_NAME "mma9551"
> #define MMA9551_IRQ_NAME "mma9551_event"
> -#define MMA9551_GPIO_NAME "mma9551_int"
> #define MMA9551_GPIO_COUNT 4
>
> /* Tilt application (inclination in IIO terms). */
> @@ -418,8 +417,7 @@ static int mma9551_gpio_probe(struct iio_dev *indio_dev)
> struct device *dev = &data->client->dev;
>
> for (i = 0; i < MMA9551_GPIO_COUNT; i++) {
> - gpio = devm_gpiod_get_index(dev, MMA9551_GPIO_NAME, i,
> - GPIOD_IN);
> + gpio = devm_gpiod_get_index(dev, NULL, i, GPIOD_IN);
> if (IS_ERR(gpio)) {
> dev_err(dev, "acpi gpio get index failed\n");
> return PTR_ERR(gpio);
--
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