Message ID | 20181129181519.15681-1-alexander.sverdlin@nokia.com |
---|---|
State | Changes Requested |
Headers | show |
Series | mtd: spi-nor: Provide default address width and latency for map selection | expand |
On Thu, 29 Nov 2018 18:15:34 +0000 "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@nokia.com> wrote: > JESD216 allows "variable address length" and "variable latency" in > Configuration Detection Command Descriptors, in other words "as-is". > And they are still unset during Sector Map Parameter Table parsing, > which led to "map_id" determined erroneously as 0 for, e.g. S25FS128S. > > Fixes: b038e8e3b ("mtd: spi-nor: parse SFDP Sector Map Parameter Table") > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com> > --- > drivers/mtd/spi-nor/spi-nor.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c > index 828d03e..5557c89 100644 > --- a/drivers/mtd/spi-nor/spi-nor.c > +++ b/drivers/mtd/spi-nor/spi-nor.c > @@ -2893,6 +2893,16 @@ static const u32 *spi_nor_get_map_in_use(struct spi_nor *nor, const u32 *smpt) > nor->read_opcode = SMPT_CMD_OPCODE(smpt[i]); > addr = smpt[i + 1]; > > + /* > + * JESD216 allows to omit particular address length or latency > + * specification in the header and at this point they are still > + * unset, so we need some heuristics. One example is S25FS128S. > + */ > + if (!nor->addr_width) > + nor->addr_width = 3; > + if (!nor->read_dummy) > + nor->read_dummy = 8; > + Looks like the same problem was reported by Yogesh here [1]. One more proof that parsing SFDP is not trivial. I mean, what's the point of defining a generic tables to describe NOR capabilities if you then depend on vendor/chip specific init to read those tables... Anyway, I think this sort of initialization should be placed in a pre_sfdp() fixup hook, as getting the right values likely requires reading some volatile/non-volatile regs. > err = spi_nor_read_raw(nor, addr, 1, &data_byte); > if (err) > goto out; [1]https://lkml.org/lkml/2018/10/22/354
Hello Boris! On 30/11/2018 11:40, Boris Brezillon wrote: >> + /* >> + * JESD216 allows to omit particular address length or latency >> + * specification in the header and at this point they are still >> + * unset, so we need some heuristics. One example is S25FS128S. >> + */ >> + if (!nor->addr_width) >> + nor->addr_width = 3; >> + if (!nor->read_dummy) >> + nor->read_dummy = 8; >> + > Looks like the same problem was reported by Yogesh here [1]. One more This is indeed the same problem, although I was not aware of the [1] discussion. > proof that parsing SFDP is not trivial. I mean, what's the point of > defining a generic tables to describe NOR capabilities if you then > depend on vendor/chip specific init to read those tables... > > Anyway, I think this sort of initialization should be placed in a > pre_sfdp() fixup hook, as getting the right values likely requires This is still on my TODO list, to learn about new hooks. > reading some volatile/non-volatile regs. This is the same instruction 65h which is used to read regs and which appears in SMPT headers, it is a chicken-egg problem. Therefore, I don't know if it's possible to provide smarter heuristics here. But without it Spansion S25FS-S Family is now broken by SFDP. >> err = spi_nor_read_raw(nor, addr, 1, &data_byte); >> if (err) >> goto out; > [1]https://lkml.org/lkml/2018/10/22/354 >
On Mon, 3 Dec 2018 08:03:18 +0000 "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@nokia.com> wrote: > Hello Boris! > > On 30/11/2018 11:40, Boris Brezillon wrote: > >> + /* > >> + * JESD216 allows to omit particular address length or latency > >> + * specification in the header and at this point they are still > >> + * unset, so we need some heuristics. One example is S25FS128S. > >> + */ > >> + if (!nor->addr_width) > >> + nor->addr_width = 3; > >> + if (!nor->read_dummy) > >> + nor->read_dummy = 8; > >> + > > Looks like the same problem was reported by Yogesh here [1]. One more > > This is indeed the same problem, although I was not aware of the [1] discussion. > > > proof that parsing SFDP is not trivial. I mean, what's the point of > > defining a generic tables to describe NOR capabilities if you then > > depend on vendor/chip specific init to read those tables... > > > > Anyway, I think this sort of initialization should be placed in a > > pre_sfdp() fixup hook, as getting the right values likely requires > > This is still on my TODO list, to learn about new hooks. ->pre_sfdp() does not exist yet, but I'm about to add it for other reasons, and it looks like a good place to put this sort of initialization. > > > reading some volatile/non-volatile regs. > > This is the same instruction 65h which is used to read regs and which > appears in SMPT headers, it is a chicken-egg problem. Oh, right, I remember now. Not a smart decision from Spansion :-/. > > Therefore, I don't know if it's possible to provide smarter heuristics > here. Maybe: ref_cr1 = read_CR1_using_RDCR() for_each_possible_dummy_and_addr_width cr1 = read_CR1_using_RDAR() if (cr1 == ref_cr1) break; > But without it Spansion S25FS-S Family is now broken by SFDP. Do you have [1] in your tree? IIRC, this fixed Yogesh issue. [1]https://patchwork.ozlabs.org/patch/994765/
Hi! On 03/12/2018 09:23, Boris Brezillon wrote: >> This is the same instruction 65h which is used to read regs and which >> appears in SMPT headers, it is a chicken-egg problem. > Oh, right, I remember now. Not a smart decision from Spansion :-/. > >> Therefore, I don't know if it's possible to provide smarter heuristics >> here. > Maybe: > > ref_cr1 = read_CR1_using_RDCR() > > for_each_possible_dummy_and_addr_width > cr1 = read_CR1_using_RDAR() > if (cr1 == ref_cr1) > break; > > >> But without it Spansion S25FS-S Family is now broken by SFDP. > Do you have [1] in your tree? IIRC, this fixed Yogesh issue. > > [1]https://patchwork.ozlabs.org/patch/994765/ This is definitely unrelated, in my case SMPT is happily processed leading to completely wrong mapping because command 65h with addr_width == 0 always returns 0.
Hi! On 03/12/2018 09:23, Boris Brezillon wrote: >> This is the same instruction 65h which is used to read regs and which >> appears in SMPT headers, it is a chicken-egg problem. > Oh, right, I remember now. Not a smart decision from Spansion :-/. > >> Therefore, I don't know if it's possible to provide smarter heuristics >> here. > Maybe: > > ref_cr1 = read_CR1_using_RDCR() > > for_each_possible_dummy_and_addr_width > cr1 = read_CR1_using_RDAR() > if (cr1 == ref_cr1) > break; This will not work, as default value for CR1(N)V is 0 and that is the value one gets with incorrect addr_width as well.
On Mon, 3 Dec 2018 08:37:17 +0000 "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@nokia.com> wrote: > Hi! > > On 03/12/2018 09:23, Boris Brezillon wrote: > >> This is the same instruction 65h which is used to read regs and which > >> appears in SMPT headers, it is a chicken-egg problem. > > Oh, right, I remember now. Not a smart decision from Spansion :-/. > > > >> Therefore, I don't know if it's possible to provide smarter heuristics > >> here. > > Maybe: > > > > ref_cr1 = read_CR1_using_RDCR() > > > > for_each_possible_dummy_and_addr_width > > cr1 = read_CR1_using_RDAR() > > if (cr1 == ref_cr1) > > break; > > This will not work, as default value for CR1(N)V is 0 and that is the value > one gets with incorrect addr_width as well. > How about: // set the WE bit in SR1 so that SR1 is not 0 write_enable() ref_sr1 = read_SR1_using_RDSR1() for_each_possible_dummy_and_addr_width sr1 = read_SR1_using_RDAR() if (sr1 == ref_sr1) break; write_disable()
On Mon, 3 Dec 2018 10:08:14 +0100 Boris Brezillon <boris.brezillon@bootlin.com> wrote: > On Mon, 3 Dec 2018 08:37:17 +0000 > "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@nokia.com> > wrote: > > > Hi! > > > > On 03/12/2018 09:23, Boris Brezillon wrote: > > >> This is the same instruction 65h which is used to read regs and which > > >> appears in SMPT headers, it is a chicken-egg problem. > > > Oh, right, I remember now. Not a smart decision from Spansion :-/. > > > > > >> Therefore, I don't know if it's possible to provide smarter heuristics > > >> here. > > > Maybe: > > > > > > ref_cr1 = read_CR1_using_RDCR() > > > > > > for_each_possible_dummy_and_addr_width > > > cr1 = read_CR1_using_RDAR() > > > if (cr1 == ref_cr1) > > > break; > > > > This will not work, as default value for CR1(N)V is 0 and that is the value > > one gets with incorrect addr_width as well. > > > > How about: > > // set the WE bit in SR1 so that SR1 is not 0 > write_enable() > > ref_sr1 = read_SR1_using_RDSR1() > for_each_possible_dummy_and_addr_width > sr1 = read_SR1_using_RDAR() > if (sr1 == ref_sr1) > break; Oh, and you should read CR2 to make sure AL and RL fields match the selected addr/dummy values. > > write_disable()
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c index 828d03e..5557c89 100644 --- a/drivers/mtd/spi-nor/spi-nor.c +++ b/drivers/mtd/spi-nor/spi-nor.c @@ -2893,6 +2893,16 @@ static const u32 *spi_nor_get_map_in_use(struct spi_nor *nor, const u32 *smpt) nor->read_opcode = SMPT_CMD_OPCODE(smpt[i]); addr = smpt[i + 1]; + /* + * JESD216 allows to omit particular address length or latency + * specification in the header and at this point they are still + * unset, so we need some heuristics. One example is S25FS128S. + */ + if (!nor->addr_width) + nor->addr_width = 3; + if (!nor->read_dummy) + nor->read_dummy = 8; + err = spi_nor_read_raw(nor, addr, 1, &data_byte); if (err) goto out;
JESD216 allows "variable address length" and "variable latency" in Configuration Detection Command Descriptors, in other words "as-is". And they are still unset during Sector Map Parameter Table parsing, which led to "map_id" determined erroneously as 0 for, e.g. S25FS128S. Fixes: b038e8e3b ("mtd: spi-nor: parse SFDP Sector Map Parameter Table") Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com> --- drivers/mtd/spi-nor/spi-nor.c | 10 ++++++++++ 1 file changed, 10 insertions(+)