Re: [PATCH] mtd: nand: vf610: Check the return value from clk_prepare_enable()

[Boris Brezillon <boris.brezillon@free-electrons.com>]

Le Mon, 17 Jul 2017 17:55:59 -0300,
Fabio Estevam <festevam@gmail.com> a écrit :

> From: Fabio Estevam <fabio.estevam@nxp.com>
> 
> clk_prepare_enable() may fail, so we should better check its return value
> and propagate it in the case of error.
> 
> Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
> ---
>  drivers/mtd/nand/vf610_nfc.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/vf610_nfc.c b/drivers/mtd/nand/vf610_nfc.c
> index 744ab10..9e49672 100644
> --- a/drivers/mtd/nand/vf610_nfc.c
> +++ b/drivers/mtd/nand/vf610_nfc.c
> @@ -814,12 +814,16 @@ static int vf610_nfc_suspend(struct device *dev)
>  
>  static int vf610_nfc_resume(struct device *dev)
>  {
> +	int err;
> +
>  	struct mtd_info *mtd = dev_get_drvdata(dev);
>  	struct vf610_nfc *nfc = mtd_to_nfc(mtd);
>  
>  	pinctrl_pm_select_default_state(dev);

AFAICT pinctrl_pm_select_default_state() can also fail. What makes it
different from clk_prepare_enable() failures?

>  
> -	clk_prepare_enable(nfc->clk);
> +	err = clk_prepare_enable(nfc->clk);
> +	if (err)
> +		return err;
>

I guess the idea was that clk_prepare_enabled already succeeded at probe
time and there was not real reason for it to fail at resume time. But
extra checks are never bad. BTW, I don't remember what happens if
->resume() returns an error. Does it prevent the whole system from
resuming or just make this specific device unusable?

>  	vf610_nfc_preinit_controller(nfc);
>  	vf610_nfc_init_controller(nfc);