[PATCH] mtd: nand: orion: fix clk handling

[Uwe Kleine-König]

Hello Simon,

On Sun, Mar 12, 2017 at 10:34:06PM +0100, Simon Baatz wrote:
> The clk handling in orion_nand.c had two problems:
> 
> - In the probe function, clk_put() was called for an enabled clock,
>   which violates the API (see documentation for clk_put() in
>   include/linux/clk.h)
> 
> - In the error path of the probe function, clk_put() could be called
>   twice for the same clock.
> 
> In order to clean this up, use the managed function devm_clk_get() and
> store the pointer to the clk in the driver data.
> 
> Fixes: baffab28b13120694fa3ebab08d3e99667a851d2 ('ARM: Orion: fix driver probe error handling with respect to clk')
> Cc: <stable at vger.kernel.org> # v4.5+
> Signed-off-by: Simon Baatz <gmbnomis at gmail.com>
> ---
>  drivers/mtd/nand/orion_nand.c | 42 +++++++++++++++++++++---------------------
>  1 file changed, 21 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/mtd/nand/orion_nand.c b/drivers/mtd/nand/orion_nand.c
> index 4a91c5d000be..b355aa738fae 100644
> --- a/drivers/mtd/nand/orion_nand.c
> +++ b/drivers/mtd/nand/orion_nand.c
> @@ -23,6 +23,11 @@
>  #include <asm/sizes.h>
>  #include <linux/platform_data/mtd-orion_nand.h>
>  
> +struct orion_nand_info {
> +	struct nand_chip chip;
> +	struct clk       *clk;
> +};
> +
>  static void orion_nand_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl)
>  {
>  	struct nand_chip *nc = mtd_to_nand(mtd);
> @@ -75,20 +80,21 @@ static void orion_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
>  
>  static int __init orion_nand_probe(struct platform_device *pdev)
>  {
> +	struct orion_nand_info *info;
>  	struct mtd_info *mtd;
>  	struct nand_chip *nc;
>  	struct orion_nand_data *board;
>  	struct resource *res;
> -	struct clk *clk;
>  	void __iomem *io_base;
>  	int ret = 0;
>  	u32 val = 0;
>  
> -	nc = devm_kzalloc(&pdev->dev,
> -			sizeof(struct nand_chip),
> +	info = devm_kzalloc(&pdev->dev,
> +			sizeof(struct orion_nand_info),
>  			GFP_KERNEL);
> -	if (!nc)
> +	if (!info)
>  		return -ENOMEM;
> +	nc = &info->chip;
>  	mtd = nand_to_mtd(nc);
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -145,15 +151,13 @@ static int __init orion_nand_probe(struct platform_device *pdev)
>  	if (board->dev_ready)
>  		nc->dev_ready = board->dev_ready;
>  
> -	platform_set_drvdata(pdev, mtd);
> +	platform_set_drvdata(pdev, info);
>  
>  	/* Not all platforms can gate the clock, so it is not
>  	   an error if the clock does not exists. */
> -	clk = clk_get(&pdev->dev, NULL);
> -	if (!IS_ERR(clk)) {
> -		clk_prepare_enable(clk);
> -		clk_put(clk);
> -	}
> +	info->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (!IS_ERR(info->clk))
> +		clk_prepare_enable(info->clk);

Orthogonal to your patch I suggest:

-	info->clk = devm_clk_get(&pdev->dev, NULL);
-	if (!IS_ERR(info->clk))
-		clk_prepare_enable(info->clk);
+	info->clk = devm_clk_get_optional(&pdev->dev, NULL);
+	if (IS_ERR(info->clk)) {
+		ret = PTR_ERR(info->clk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(...);
+		return ret;
+	}

to correct error handling.
(I didn't check if a plain return is right here, and also other users of
info->clk need adaption.)

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |