Re: [PATCH] mtd: gpmi-nand: do not fail setting ONFI timing mode if available

Boris Brezillon
2017-07-13T20:15:44Z

Hi Miquel,

Le Thu, 13 Jul 2017 21:20:30 +0200,
Miquel Raynal <miquel.raynal@free-electrons.com> a écrit :

> GPMI NFC driver fails to apply timing mode if the ->onfi_get_features()
> does not return the mode that was previously applied.
>
> We can assume that a nand chip supports a timing as long as it is
> read from the ONFI parameter page. Reading back a different mode than
> the one previously applied does not mean the mode is unsupported but
> that the nand chip does not implement the ONFI feature because it
> probably does not need to.
>
> The output of ->onfi_get_feature() is irrelevant so delete it.

Having the NAND part that is not supporting the get/set(timing_mode)
feature explicitly mentioned in the commit message would help reviewers
understand why this patch is needed.

Also mention that, even though the SET/GET_FEATURES(timing_mode) is
marked as required in the ONFI spec, this Macronix chip does not
support it which could be considered as a bug.

Regards,

Boris

>
> Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
> ---
> drivers/mtd/nand/gpmi-nand/gpmi-lib.c | 7 -------
> 1 file changed, 7 deletions(-)
>
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> index 141bd70a49c2..4d137145439c 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> @@ -939,13 +939,6 @@ static int enable_edo_mode(struct gpmi_nand_data *this, int mode)
> if (ret)
> goto err_out;
>
> - /* [2] send GET FEATURE command to double-check the timing mode */
> - memset(feature, 0, ONFI_SUBFEATURE_PARAM_LEN);
> - ret = nand->onfi_get_features(mtd, nand,
> - ONFI_FEATURE_ADDR_TIMING_MODE, feature);
> - if (ret || feature[0] != mode)
> - goto err_out;
> -
> nand->select_chip(mtd, -1);
>
> /* [3] set the main IO clock, 100MHz for mode 5, 80MHz for mode 4. */