Hi Jean,
On Thu, Feb 28, 2013 at 12:01:40PM +0100, Jean Delvare wrote:
> GPIOs may not be available immediately when i2c-gpio looks for them.
> Implement support for deferred probing so that probing can be
> attempted again later when GPIO pins are finally available.
>
> Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
> Cc: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx>
> ---
> A little more changes were needed than I initially thought, because we
> want to check the pins before we allocate memory. Otherwise we would
> have a possibly large number of memory allocation and freeing cycles
> until GPIO pins are finally available.
>
> I wrote this quite some time ago already, but I do not have any system
> to test it. I would appreciate if one or more users of the i2c-gpio
> driver could give it a try and confirm it works as intended, or at
> least doesn't introduce any regression. Thanks.
>
> drivers/i2c/busses/i2c-gpio.c | 75 ++++++++++++++++++++++++++++--------------
> 1 file changed, 50 insertions(+), 25 deletions(-)
>
> --- linux-3.8-rc2.orig/drivers/i2c/busses/i2c-gpio.c 2013-01-09 22:26:30.031060312 +0100
> +++ linux-3.8-rc2/drivers/i2c/busses/i2c-gpio.c 2013-01-09 22:32:59.950308645 +0100
> @@ -85,23 +85,29 @@ static int i2c_gpio_getscl(void *data)
> return gpio_get_value(pdata->scl_pin);
> }
>
> -static int of_i2c_gpio_probe(struct device_node *np,
> - struct i2c_gpio_platform_data *pdata)
> +static int of_i2c_gpio_get_pins(struct device_node *np,
> + unsigned int *sda_pin, unsigned int *scl_pin)
GPIOs are expressed via int.
> + ret = gpio_request(sda_pin, "sda");
> + if (ret) {
> + if (ret == -EINVAL)
> + ret = -EPROBE_DEFER; /* Try again later */
Would gpio_request_array() make the code simpler?
Thanks,
Wolfram
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