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

Uwe Kleine-König
2017-03-13T07:13:13Z

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@vger.kernel.org> # v4.5+
> Signed-off-by: Simon Baatz <gmbnomis@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

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