linux-kernel - RE: [PATCH] i2c: imx: defer probe if bus recovery GPIOs are not ready

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Message-ID: <AM2PR04MB0770E6FB2035B855F216FE108FCC0@AM2PR04MB0770.eurprd04.prod.outlook.com>
Date:   Tue, 27 Sep 2016 18:31:14 +0000
From:   Leo Li <leoyang.li@....com>
To:     Stefan Agner <stefan@...er.ch>,
        "wsa@...-dreams.de" <wsa@...-dreams.de>
CC:     "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] i2c: imx: defer probe if bus recovery GPIOs are not ready



> -----Original Message-----
> From: Stefan Agner [mailto:stefan@...er.ch]
> Sent: Monday, September 26, 2016 7:19 PM
> To: wsa@...-dreams.de
> Cc: Leo Li <leoyang.li@....com>; linux-i2c@...r.kernel.org; u.kleine-
> koenig@...gutronix.de; linux-kernel@...r.kernel.org; Stefan Agner
> <stefan@...er.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@...er.ch>

Acked-by: Li Yang <leoyang.li@....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