[PATCH 1/2] mtd: nand: make Samsung SLC NAND usable again
Boris Brezillon
boris.brezillon at free-electrons.com
Tue Aug 29 06:41:44 PDT 2017
On Tue, 29 Aug 2017 15:18:07 +0200
Lothar Waßmann <LW at KARO-electronics.de> wrote:
> Hi,
>
> On Tue, 29 Aug 2017 14:16:58 +0200 Boris Brezillon wrote:
> > Hi Lothar,
> >
> > On Tue, 29 Aug 2017 12:17:12 +0200
> > Lothar Waßmann <LW at KARO-electronics.de> wrote:
> >
> > > commit c51d0ac59f24 ("mtd: nand: Move Samsung specific init/detection
> > > logic in nand_samsung.c") introduced a regression for Samsung SLC NAND
> > > chips. Prior to this commit chip->bits_per_cell was initialized by calling
> > > nand_get_bits_per_cell() before using nand_is_slc().
> > > With the offending commit this call is skipped, leaving
> > > chip->bits_per_cell cleared to zero when the manufacturer specific
> > > '.detect' function calls nand_is_slc() which in turn interprets
> > > bits_per_cell != 1 as indication for an MLC chip.
> > > The effect is that e.g. a K9F1G08U0F NAND chip is falsely detected as
> > > MLC NAND with 4KiB page size rather than SLC with 2KiB page size.
> >
> > Oops, sorry for this regression.
> >
> > >
> > > Add a call to nand_get_bits_per_cell() before calling the .detect hook
> > > function in nand_manufacturer_detect(), so that the nand_is_slc()
> > > calls in the manufacturer specific code will return correct results.
> >
> > I'd prefer a different solution (see below).
> >
> > >
> > > Signed-off-by: Lothar Waßmann <LW at KARO-electronics.de>
> > > ---
> > > drivers/mtd/nand/nand_base.c | 7 +++++--
> > > 1 file changed, 5 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> > > index 9900476..bcc8cef1 100644
> > > --- a/drivers/mtd/nand/nand_base.c
> > > +++ b/drivers/mtd/nand/nand_base.c
> > > @@ -3820,10 +3820,13 @@ static void nand_manufacturer_detect(struct nand_chip *chip)
> > > * nand_decode_ext_id() otherwise.
> > > */
> > > if (chip->manufacturer.desc && chip->manufacturer.desc->ops &&
> > > - chip->manufacturer.desc->ops->detect)
> > > + chip->manufacturer.desc->ops->detect) {
> > > + /* The 3rd id byte holds MLC / multichip data */
> > > + chip->bits_per_cell = nand_get_bits_per_cell(chip->id.data[2]);
> >
> > I'd prefer not to force this bit_per_cell detection here. How about
> > explicitly calling nand_decode_ext_id() from the samsung and hynix
> > ->detect() hooks (see proposed diff below)?
> >
> I chose the same place in the code flow where this initialization had
> been before. And it does only that portion of nand_decode_ext_id() that
> was executed prior to the vendor specific code in the old code.
> A call to nand_decode_ext_id() would do more than has been done
> previously.
My main concern is, can we be sure this portion of the 3rd byte is
always used to encode the bits-per-cell information? NAND vendors tend
to take liberties with the NAND ids fields and I fear we'll someday have
a NAND that does not follow this encoding scheme.
This being said, find_full_id_nand() also calls
nand_get_bits_per_cell() even though it's using full-id information for
other characteristics, which tend to confirm noone ever had a NAND
abusing this bits-per-cell field.
I'll just take your patch as is and add Cc-stable a Fixes tags.
Note that I'm planning to rework the NAND detection logic a bit to let
manufacturer code tweak the characteristics even if the NAND is ONFI or
JEDEC compliant (see below).
>
> I prefer not to have to rely on every single manufacturer dependent
> code calling this function on its own. But you are the maintainer and
> have to decide finally.
> With my second patch it should be easy to spot when the call is missing
> though.
Yep, your second patch is fine.
>
> Another alternative were to let nand_is_slc() do the initialization
> from id_data when it is first called (bits_per_cell == 0).
Well, you could do
return bits_per_cell <= 1
but I think your WARN() is appropriate (though I'd put it somewhere
else, like just after the detection logic).
--->8---
diff --git a/drivers/mtd/nand/nand_amd.c b/drivers/mtd/nand/nand_amd.c
index 170403a3bfa8..95342862fd31 100644
--- a/drivers/mtd/nand/nand_amd.c
+++ b/drivers/mtd/nand/nand_amd.c
@@ -21,7 +21,9 @@ static void amd_nand_decode_id(struct nand_chip *chip)
{
struct mtd_info *mtd = nand_to_mtd(chip);
- nand_decode_ext_id(chip);
+ /* Skip ID decoding for JEDEC or ONFI chips. */
+ if (chip->onfi_version || chip->jedec_version)
+ return;
/*
* Check for Spansion/AMD ID + repeating 5th, 6th byte since
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index c6c18b82f8f4..0640687b50c2 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3982,9 +3982,9 @@ static bool find_full_id_nand(struct nand_chip *chip,
}
/*
- * Manufacturer detection. Only used when the NAND is not ONFI or JEDEC
- * compliant and does not have a full-id or legacy-id entry in the nand_ids
- * table.
+ * Manufacturer detection. This follows the regular ONFI, JEDEC or ID decoding
+ * detection and allows driver specific code to tweak the NAND chip
+ * characteristics.
*/
static void nand_manufacturer_detect(struct nand_chip *chip)
{
@@ -3995,8 +3995,6 @@ static void nand_manufacturer_detect(struct nand_chip *chip)
if (chip->manufacturer.desc && chip->manufacturer.desc->ops &&
chip->manufacturer.desc->ops->detect)
chip->manufacturer.desc->ops->detect(chip);
- else
- nand_decode_ext_id(chip);
}
/*
@@ -4128,7 +4126,7 @@ static int nand_detect(struct nand_chip *chip, struct nand_flash_dev *type)
chip->chipsize = (uint64_t)type->chipsize << 20;
if (!type->pagesize)
- nand_manufacturer_detect(chip);
+ nand_decode_ext_id(chip)
else
nand_decode_id(chip, type);
@@ -4136,6 +4134,7 @@ static int nand_detect(struct nand_chip *chip, struct nand_flash_dev *type)
chip->options |= type->options;
ident_done:
+ nand_manufacturer_detect(chip);
if (chip->options & NAND_BUSWIDTH_AUTO) {
WARN_ON(busw & NAND_BUSWIDTH_16);
diff --git a/drivers/mtd/nand/nand_hynix.c b/drivers/mtd/nand/nand_hynix.c
index b12dc7325378..b77b45c4ed03 100644
--- a/drivers/mtd/nand/nand_hynix.c
+++ b/drivers/mtd/nand/nand_hynix.c
@@ -547,6 +547,10 @@ static void hynix_nand_decode_id(struct nand_chip *chip)
bool valid_jedecid;
u8 tmp;
+ /* Skip ID decoding for JEDEC or ONFI chips. */
+ if (chip->onfi_version || chip->jedec_version)
+ return;
+
/*
* Exclude all SLC NANDs from this advanced detection scheme.
* According to the ranges defined in several datasheets, it might
@@ -554,10 +558,8 @@ static void hynix_nand_decode_id(struct nand_chip *chip)
* If that the case rework the test to let SLC NANDs go through the
* detection process.
*/
- if (chip->id.len < 6 || nand_is_slc(chip)) {
- nand_decode_ext_id(chip);
+ if (chip->id.len < 6 || nand_is_slc(chip))
return;
- }
/* Extract pagesize */
mtd->writesize = 2048 << (chip->id.data[3] & 0x03);
diff --git a/drivers/mtd/nand/nand_samsung.c b/drivers/mtd/nand/nand_samsung.c
index 1e0755997762..9da0a2101d63 100644
--- a/drivers/mtd/nand/nand_samsung.c
+++ b/drivers/mtd/nand/nand_samsung.c
@@ -21,6 +21,10 @@ static void samsung_nand_decode_id(struct nand_chip *chip)
{
struct mtd_info *mtd = nand_to_mtd(chip);
+ /* Skip ID decoding for JEDEC or ONFI chips. */
+ if (chip->onfi_version || chip->jedec_version)
+ return;
+
/* New Samsung (6 byte ID): Samsung K9GAG08U0F (p.44) */
if (chip->id.len == 6 && !nand_is_slc(chip) &&
chip->id.data[5] != 0x00) {
@@ -89,8 +93,6 @@ static void samsung_nand_decode_id(struct nand_chip *chip)
chip->ecc_step_ds = 0;
}
}
- } else {
- nand_decode_ext_id(chip);
}
}
diff --git a/drivers/mtd/nand/nand_toshiba.c b/drivers/mtd/nand/nand_toshiba.c
index fa787ba38dcd..1aa56363bc16 100644
--- a/drivers/mtd/nand/nand_toshiba.c
+++ b/drivers/mtd/nand/nand_toshiba.c
@@ -21,7 +21,9 @@ static void toshiba_nand_decode_id(struct nand_chip *chip)
{
struct mtd_info *mtd = nand_to_mtd(chip);
- nand_decode_ext_id(chip);
+ /* Skip ID decoding for JEDEC or ONFI chips. */
+ if (chip->onfi_version || chip->jedec_version)
+ return;
/*
* Toshiba 24nm raw SLC (i.e., not BENAND) have 32B OOB per
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