2018-04-11 03:01:44

by Jia-Ju Bai

Subject: [PATCH] mtd: nand: diskonchip: Replace mdelay with usleep_range in doc_probe

doc_probe() is never called in atomic context.

doc_probe() is only called by init_nanddoc(), which is only set as
a parameter of module_init().
This function is not called in atomic context.

Despite never getting called from atomic context, doc_probe()
calls mdelay() to busily wait.
This is not necessary and can be replaced with usleep_range() to
avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/mtd/nand/diskonchip.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/diskonchip.c b/drivers/mtd/nand/diskonchip.c
index c3aa53c..2679bc4 100644
--- a/drivers/mtd/nand/diskonchip.c
+++ b/drivers/mtd/nand/diskonchip.c
@@ -1482,12 +1482,12 @@ static int __init doc_probe(unsigned long physadr)
WriteDOC(tmp, virtadr, Mplus_DOCControl);
WriteDOC(~tmp, virtadr, Mplus_CtrlConfirm);

- mdelay(1);
+ usleep_range(1000, 2000);
/* Enable the Millennium Plus ASIC */
tmp = DOC_MODE_NORMAL | DOC_MODE_MDWREN | DOC_MODE_RST_LAT | DOC_MODE_BDECT;
WriteDOC(tmp, virtadr, Mplus_DOCControl);
WriteDOC(~tmp, virtadr, Mplus_CtrlConfirm);
- mdelay(1);
+ usleep_range(1000, 2000);

ChipID = ReadDOC(virtadr, ChipID);

--
1.9.1

2018-04-22 17:28:22

by Boris Brezillon

Subject: Re: [PATCH] mtd: nand: diskonchip: Replace mdelay with usleep_range in doc_probe

On Wed, 11 Apr 2018 10:57:57 +0800
Jia-Ju Bai <[email protected]> wrote:

> doc_probe() is never called in atomic context.
>
> doc_probe() is only called by init_nanddoc(), which is only set as
> a parameter of module_init().
> This function is not called in atomic context.
>
> Despite never getting called from atomic context, doc_probe()
> calls mdelay() to busily wait.
> This is not necessary and can be replaced with usleep_range() to
> avoid busy waiting.
>
> This is found by a static analysis tool named DCNS written by myself.
> And I also manually check it.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> ---
> drivers/mtd/nand/diskonchip.c | 4 ++--

Applied to nand/next after fixing the subject prefix and the file path.

Thanks,

Boris

> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mtd/nand/diskonchip.c b/drivers/mtd/nand/diskonchip.c
> index c3aa53c..2679bc4 100644
> --- a/drivers/mtd/nand/diskonchip.c
> +++ b/drivers/mtd/nand/diskonchip.c
> @@ -1482,12 +1482,12 @@ static int __init doc_probe(unsigned long physadr)
> WriteDOC(tmp, virtadr, Mplus_DOCControl);
> WriteDOC(~tmp, virtadr, Mplus_CtrlConfirm);
>
> - mdelay(1);
> + usleep_range(1000, 2000);
> /* Enable the Millennium Plus ASIC */
> tmp = DOC_MODE_NORMAL | DOC_MODE_MDWREN | DOC_MODE_RST_LAT | DOC_MODE_BDECT;
> WriteDOC(tmp, virtadr, Mplus_DOCControl);
> WriteDOC(~tmp, virtadr, Mplus_CtrlConfirm);
> - mdelay(1);
> + usleep_range(1000, 2000);
>
> ChipID = ReadDOC(virtadr, ChipID);
>