Re: [PATCH 1/2] Fix FSL NAND driver to read all ONFI parameter pages

Miquel Raynal
2018-05-02T08:10:27Z

Hi Jane,

On Tue, 1 May 2018 05:01:23 +0000, "Wan, Jane (Nokia - US/Sunnyvale)"
<jane.wan@nokia.com> wrote:

> Hi Miquèl and Boris,
>
> Thank you for your response and feedback. I've modified the fix based on your comments.
> Please see the updated patch file at the end of this message (also in attachment).
> My answers to your comments/questions are inline in the previous message.

Usually we answer inline in each e-mail, then we post a new version
with a version counter incremented (use the '-v2- of 'git format-patch'
to add the '[PATCH v2 x/y]' prefix automatically). Reposting is
important as maintainers use 'patchwork' to follow the evolution of
each patch. So in your case, nothing shows that you posted a v2.

>
> Here is the answer to Boris question in another email thread:
>
> > What if some NANDs have 4 or more copies of the param page?
> [Jane] The ONFI spec defines that the parameter page and its two redundant copies are mandatory.
> The additional redundant pages are optional. Currently, the FSL NAND driver only reads the first
> parameter page. This patch is to fix the driver to meet the mandatory requirement in the spec.
> We got a batch of particularly bad NAND chips recently and we needed these changes to make them
> work reliably over temperature. The patch was verified using these bad chips.

I think Boris' remark was much more general than just this use case.
The whole logic of tailoring ->cmdfunc() in each driver by guessing the
data length, while there is absolutely no indication of it in this hook
is broken. The core is moving to a new interface called ->exec_op(),
and we would welcome a migration of this driver to this hook, that
would be much much more easy to maintain for everyone.

Thanks,
Miquèl

>
> Best regards,
> Jane
>
> Updated patch:
> From 701de4146aa6355c951e97a77476e12d2da56d42 Mon Sep 17 00:00:00 2001
> From: Jane Wan <Jane.Wan@nokia.com>
> Date: Mon, 30 Apr 2018 13:30:46 -0700
> Subject: [PATCH 1/2] mtd: rawnand: fsl_ifc: fix FSL NAND driver to read all
> ONFI parameter pages
>
> Per ONFI specification (Rev. 4.0), if the CRC of the first parameter page
> read is not valid, the host should read redundant parameter page copies.
> Fix FSL NAND driver to read the two redundant copies which are mandatory
> in the specification.
>
> Signed-off-by: Jane Wan <Jane.Wan@nokia.com>
> ---
> drivers/mtd/nand/raw/fsl_ifc_nand.c | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/fsl_ifc_nand.c b/drivers/mtd/nand/raw/fsl_ifc_nand.c
> index 61aae02..98aac1f 100644
> --- a/drivers/mtd/nand/raw/fsl_ifc_nand.c
> +++ b/drivers/mtd/nand/raw/fsl_ifc_nand.c
> @@ -342,9 +342,16 @@ static void fsl_ifc_cmdfunc(struct mtd_info *mtd, unsigned int command,
>
> case NAND_CMD_READID:
> case NAND_CMD_PARAM: {
> + /*
> + * For READID, read 8 bytes that are currently used.
> + * For PARAM, read all 3 copies of 256-bytes pages.
> + */
> + int len = 8;
> int timing = IFC_FIR_OP_RB;
> - if (command == NAND_CMD_PARAM)
> + if (command == NAND_CMD_PARAM) {
> timing = IFC_FIR_OP_RBCD;
> + len = 256 * 3;
> + }
>
> ifc_out32((IFC_FIR_OP_CW0 << IFC_NAND_FIR0_OP0_SHIFT) |
> (IFC_FIR_OP_UA << IFC_NAND_FIR0_OP1_SHIFT) |
> @@ -354,12 +361,8 @@ static void fsl_ifc_cmdfunc(struct mtd_info *mtd, unsigned int command,
> &ifc->ifc_nand.nand_fcr0);
> ifc_out32(column, &ifc->ifc_nand.row3);
>
> - /*
> - * although currently it's 8 bytes for READID, we always read
> - * the maximum 256 bytes(for PARAM)
> - */
> - ifc_out32(256, &ifc->ifc_nand.nand_fbcr);
> - ifc_nand_ctrl->read_bytes = 256;
> + ifc_out32(len, &ifc->ifc_nand.nand_fbcr);
> + ifc_nand_ctrl->read_bytes = len;
>
> set_addr(mtd, 0, 0, 0);
> fsl_ifc_run_command(mtd);

--
Miquel Raynal, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering