i2c: imx: defer probe if bus recovery GPIOs are not ready

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>
---
This is an actual issue on NXP Vybrid devices on which the GPIO
driver gets loaded rather later.

--
Stefan

 drivers/i2c/busses/i2c-imx.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

Hello Stefan,

On Mon, Sep 26, 2016 at 05:18:58PM -0700, Stefan Agner wrote:
> 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>

Thanks
Uwe

> -----Original Message-----
> From: Stefan Agner [mailto:stefan@agner.ch]
> Sent: Monday, September 26, 2016 7:19 PM
> To: wsa@the-dreams.de
> Cc: Leo Li <leoyang.li@nxp.com>; linux-i2c@vger.kernel.org; u.kleine-
> koenig@pengutronix.de; linux-kernel@vger.kernel.org; Stefan Agner
> <stefan@agner.ch>
> Subject: [PATCH] i2c: imx: defer probe if bus recovery GPIOs are not ready
> 
> 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: Li Yang <leoyang.li@nxp.com>

> ---
> This is an actual issue on NXP Vybrid devices on which the GPIO
> driver gets loaded rather later.
> 
> --
> 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 592a8f2..47fc1f1 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1009,10 +1009,13 @@ static int i2c_imx_init_recovery_info(struct
> imx_i2c_struct *i2c_imx,
>  	rinfo->sda_gpio = of_get_named_gpio(pdev->dev.of_node, "sda-gpios",
> 0);
>  	rinfo->scl_gpio = of_get_named_gpio(pdev->dev.of_node, "scl-gpios",
> 0);
> 
> -	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 0;
>  	}
> --
> 2.10.0

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On Mon, Sep 26, 2016 at 05:18:58PM -0700, Stefan Agner wrote:
> 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>

Added stable and applied to for-current, thanks! Please consider adding
a "Fixes: <sha-id>" next time. This would be helpful.