Re: [PATCH] i2c: imx: defer probe if bus recovery GPIOs are not ready

[Stefan Agner <stefan@agner.ch>]

On 2016-11-08 16:32, Stefan Agner wrote:
> commit 533169d164c6b4c8571d0d48779f6ff6be593d72 upstream.
> 
> Some SoC might load the GPIO driver after the I2C driver and
> using the I2C bus recovery mechanism via GPIOs. In this case
> it is crucial to defer probing if the GPIO request functions
> do so, otherwise the I2C driver gets loaded without recovery
> mechanisms enabled.
> 
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Acked-by: Li Yang <leoyang.li@nxp.com>
> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
> Cc: stable@kernel.org

I forgot to mention, this should be applied to 4.4 only.

Later versions made the return value void, and it would require a larger
rework. I am mainly concerned about LTS...

--
Stefan

> ---
>  drivers/i2c/busses/i2c-imx.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index d4d8536..32fae2c 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1002,10 +1002,13 @@ static void i2c_imx_init_recovery_info(struct
> imx_i2c_struct *i2c_imx,
>  	rinfo->scl_gpio = of_get_named_gpio_flags(pdev->dev.of_node,
>  			"scl-gpios", 0, NULL);
>  
> -	if (!gpio_is_valid(rinfo->sda_gpio) ||
> -	    !gpio_is_valid(rinfo->scl_gpio) ||
> -	    IS_ERR(i2c_imx->pinctrl_pins_default) ||
> -	    IS_ERR(i2c_imx->pinctrl_pins_gpio)) {
> +	if (rinfo->sda_gpio == -EPROBE_DEFER ||
> +	    rinfo->scl_gpio == -EPROBE_DEFER) {
> +		return -EPROBE_DEFER;
> +	} else if (!gpio_is_valid(rinfo->sda_gpio) ||
> +		   !gpio_is_valid(rinfo->scl_gpio) ||
> +		   IS_ERR(i2c_imx->pinctrl_pins_default) ||
> +		   IS_ERR(i2c_imx->pinctrl_pins_gpio)) {
>  		dev_dbg(&pdev->dev, "recovery information incomplete\n");
>  		return;
>  	}