[PATCH 2/3] mtd: spi-nor: Implement die erase command logic
Krzeminski, Marcin (Nokia - PL/Wroclaw)
marcin.krzeminski at nokia.com
Fri Dec 16 05:36:49 PST 2016
> -----Original Message-----
> From: Cyrille Pitchen [mailto:cyrille.pitchen at atmel.com]
> Sent: Friday, December 16, 2016 11:52 AM
> To: Krzeminski, Marcin (Nokia - PL/Wroclaw)
> <marcin.krzeminski at nokia.com>; linux-mtd at lists.infradead.org
> Cc: rfsw-patches at mlist.nokia.com; dwmw2 at infradead.org;
> computersforpeace at gmail.com; marek.vasut at gmail.com
> Subject: Re: [PATCH 2/3] mtd: spi-nor: Implement die erase command logic
>
> Hi Marcin,
>
> Le 16/12/2016 à 07:38, Krzeminski, Marcin (Nokia - PL/Wroclaw) a écrit :
> > Cyrille,
> >
> > Sorry for late answer.
> >
> >> -----Original Message-----
> >> From: Cyrille Pitchen [mailto:cyrille.pitchen at atmel.com]
> >> Sent: Friday, December 09, 2016 6:23 PM
> >> To: Krzeminski, Marcin (Nokia - PL/Wroclaw)
> >> <marcin.krzeminski at nokia.com>; linux-mtd at lists.infradead.org
> >> Cc: rfsw-patches at mlist.nokia.com; dwmw2 at infradead.org;
> >> computersforpeace at gmail.com; marek.vasut at gmail.com
> >> Subject: Re: [PATCH 2/3] mtd: spi-nor: Implement die erase command
> >> logic
> >>
> >> Le 30/11/2016 à 19:18, Krzeminski, Marcin (Nokia - PL/Wroclaw) a écrit :
> >>>
> >>>
> >>>> -----Original Message-----
> >>>> From: Cyrille Pitchen [mailto:cyrille.pitchen at atmel.com]
> >>>> Sent: Wednesday, November 30, 2016 6:20 PM
> >>>> To: Krzeminski, Marcin (Nokia - PL/Wroclaw)
> >>>> <marcin.krzeminski at nokia.com>; linux-mtd at lists.infradead.org
> >>>> Cc: rfsw-patches at mlist.nokia.com; dwmw2 at infradead.org;
> >>>> computersforpeace at gmail.com; marek.vasut at gmail.com
> >>>> Subject: Re: [PATCH 2/3] mtd: spi-nor: Implement die erase command
> >>>> logic
> >>>>
> >>>> Le 30/11/2016 à 17:44, Krzeminski, Marcin (Nokia - PL/Wroclaw) a écrit :
> >>>>>
> >>>>>
> >>>>>> -----Original Message-----
> >>>>>> From: Cyrille Pitchen [mailto:cyrille.pitchen at atmel.com]
> >>>>>> Sent: Tuesday, November 29, 2016 5:47 PM
> >>>>>> To: Krzeminski, Marcin (Nokia - PL/Wroclaw)
> >>>>>> <marcin.krzeminski at nokia.com>; linux-mtd at lists.infradead.org
> >>>>>> Cc: rfsw-patches at mlist.nokia.com; dwmw2 at infradead.org;
> >>>>>> computersforpeace at gmail.com; marek.vasut at gmail.com
> >>>>>> Subject: Re: [PATCH 2/3] mtd: spi-nor: Implement die erase
> >>>>>> command logic
> >>>>>>
> >>>>>> Hi Marcin,
> >>>>>>
> >>>>>> I know you have already answered some of my questions of IRC but
> >>>>>> I ask them again here on the mailing list so everybody can
> >>>>>> benefit from your answers.
> >>>>>>
> >>>>>> Le 24/10/2016 à 15:03, marcin.krzeminski at nokia.com a écrit :
> >>>>>>> From: Marcin Krzeminski <marcin.krzeminski at nokia.com>
> >>>>>>>
> >>>>>>> This commit implements die erase logic.
> >>>>>>> Sector at a time procedure is moved to function, then erase
> >>>>>>> algorithm will try to use die erase cmd if size and address
> >>>>>>> cover one or more dies.
> >>>>>>>
> >>>>>>
> >>>>>> I'm reading your v2 series but indeed I try to understand the
> >>>>>> purpose of the series simply because I don't know what does die
> >>>>>> erase do as compared to chip erase of sector erase.
> >>>>>> Is you series a bug fix or an optmization, maybe both?
> >>>>>
> >>>>> In current spi-nor framework when user want to erase whole flash
> (eg.
> >>>>> mtd_debug erase /dev/mtdX 0 0x8000000) framework issue chip
> erase
> >>>> cmd.
> >>>>> N25Q00 does not support chip erase, instead there was introduced
> >>>>> die erase command that can erase whole die (N25Q00 is a mulit-die
> >>>>> NOR
> >> chip).
> >>>>> So for this case this patch is a bug fix.
> >>>>> Since I have die erase command implemented it was tempting to use
> >>>>> die erase also in case where erase area cover one or more dies to
> >>>>> speed up erase process, especially when user has enabled 4KiB
> >>>>> sector. That is a small
> >>>> optimization.
> >>>>>
> >>>>> I will rewrite commit message and add those informations.
> >>>>>
> >>>>> Thanks,
> >>>>> Marcin
> >>>>>
> >>>>
> >>>> OK, then I think your patch should be split into two different patches.
> >>>>
> >>>> 1 - bug fix:
> >>>>
> >>>> The first patch introducing an explicit flag such as
> >>>> SPI_NOR_NO_CHIP_ERASE, which would be set in the relevant entries
> >>>> of the spi_nor_ids[] (see already existing flags such as
> >>>> SPI_NOR_NO_FR,
> >> SPI_NOR_NO_ERASE, ...).
> >>>>
> >>>> In spi_nor_scan():
> >>>>
> >>>> if (info->flags & USE_FSR)
> >>>> nor->flags |= SNOR_F_USE_FSR;
> >>>> if (info->flags & SPI_NOR_HAS_TB)
> >>>> nor->flags |= SNOR_F_HAS_SR_TB;
> >>>> + if (info->flags & SPI_NOR_NO_CHIP_ERASE)
> >>>> + nor->flags |= SNOR_F_NO_CHIP_ERASE;
> >>>>
> >>>> Then in spi_nor_erase():
> >>>>
> >>>> /* whole-chip erase? */
> >>>> - if (len == mtd->size) {
> >>>> + if (len == mtd->size && !(nor->flags & SNOR_F_NO_CHIP_ERASE)) {
> >>>> unsigned long timeout;
> >>>>
> >>>> So you fall into the sector erase case, no optimization yet.
> >>>>
> >>>> 2 - optimization of spi_nor_erase()
> >>>>
> >>>> In the "sector"-at-a-time erase branch, try to optimize when
> >>>> possible using die erase instead of sector erase.
> >>>>
> >>>> Each commit message describing the purpose of the patch.
> >>>
> >>>
> >>> OK, I will split patches in this way.
> >>>
> >>>>
> >>>> I would like to also handle the cases where the memory supports:
> >>>> - both chip and die erases: if so, no reason not to use chip erase on
> such
> >>>> multi-die memory.
> >>> I do not think that there are chips supporting both.
> >>> In this case two flags are needed one for disable chip erase and
> >>> another one for enabling die erase. Is that OK?
> >>
> >> I think it might be better to have 2 separated flags, at least for
> >> semantic
> >> reason: "the memory supports Die-Erase hence we don't try to use
> >> Chip- Erase" sounds a little bit odd to me.
> >
> > Let's do it with two flags then.
> >
> >>
> >> This is what I understand when I read:
> >> /* whole-chip erase? */
> >> - if (len == mtd->size) {
> >> + if (len == mtd->size && !die_erase) {
> >>
> >> Why do we try Chip-Erase only if Die-Erase is not supported?
> >
> > I assumed that there is no flash that support both.
> > Do you know one that has chip erase and die erase?
> >
>
> No, I don't but I didn't focus on erase operations so maybe some already
> exist or might exit in the future, who knows? :)
>
> Also, please have a look at Ricardo's patch:
> [v9] mtd: spi-nor: Add supported for S3AN spi-nor devices
> http://patchwork.ozlabs.org/patch/701935/
>
> This patch has recently been merged into git://github.com/spi-nor/linux.git
> so you will have to rebase your work on that tree.
Thanks for information, so git://github.com/spi-nor/linux.git should be used
As base to send spi-nor patches?
>
> Ricardo's patch already introduces a SNOR_F_NO_OP_CHIP_ERASE flag used
> from spi_nor_erase(). The only missing part is to set this flag in nor->flag
> when another dedicated flag is set in info->flags.
> Currently this SNOR_F_NO_OP_CHIP_ERASE is only set from
> s3an_nor_scan() but it should be also set from spi_nor_scan() for the
> relevant memories.
Ok.
>
> >>
> >> Reading something like "we try Chip-Erase unless Chip-Erase is not
> >> supported" is more logic, isn't it?
> >>
> >> I want to avoid the implicit assumption "Die Erase supported => Chip
> >> Erase not supported", even if it *might* be true, because it is
> >> strange when we read the code.
> >
> > Ok.
> >>
> >>>> - neither chip nor die erases.
> >>> This is supported DIE_ERASE flasg set and die_cnt == 0
> >>
> >> DIE_ERASE flag set and die_cnt == 0 meaning Chip-Erase is not supported?
> >> IHMO, semantically, it's not logical.
> >
> > Just to save yet another flag. Having so many flags make codes
> > complicated, but I agree the it I at least logical.
> >>
> >> Also discussing another topic on #mtd, it seems that some memories
> >> don't have a 4-byte address version of the Die Erase op code.
> >
> > Yes. Could be workarounded by enabling 4byte address mode just before
> > sending die erase and then disable it back.
> > The more important question is if you really one to have in upstream die
> erase?
> > It is about 30% faster than sector at time erase on some flash
> > (especially in case 4KiB sectors). From the other hand I see chips
> > that it was not faster at all (it also applies on chip erase).
> > My first version of fixing this problem was to add only the flag of disable
> chip erase.
> > See here:
> > http://lists.infradead.org/pipermail/linux-mtd/2016-October/069888.htm
> > l Maybe for now it is better to take above?
> >
> >>
> >> If so, it's preferred to use a 4-byte address Sector/Block Erase op
> >> code than to enter/exit the statefull 4-byte address mode then use
> >> the Die Erase op
> >> code: this statefull mode should be avoided as much as possible
> >> because many bootloaders expect the SPI memory to be in 3byte address
> >> mode and if a spurious reset occurs on the CPU side (but not on the
> >> memory side) those bootloaders will fail to read data from the SPI
> memory.
> >
> > Yeap, moreover similar problem you will face when you will try to add
> > QPi modes (444) to framework.
> >
>
> Entering the 4-byte address mode might be accepted as a workaround to
> allow using the Die Erase op code even on > 16MiB memory as long as the
> user can choose to disable this feature and the feature is not enabled by
> default.
> This way we don't prevent end users from using Die Erase if they want but
> we don't force them to use it if they don't want to.
>
> Indeed, Die Erase is an optimization but it is not mandatory to erase the
> memory: the slower Sector/Block Erase commands can still be used.
> However entering the 4-byte address mode to allow using the Die Erase
> command has side effects, as explained above, that might introduce
> regression.
>
> Let's imagine the case of a 2-die memory used to store 2 firmware images.
> The firmware update process could alternate between dies when writing a
> new firmware image so the current/older firmware image is still available if
> the update process fails to write the new image.
At least for Micron it is possible to do such sequence:
1. Enter 4 byte address mode.
2. Send die erase.
3. Exit 4 byte address mode.
4. Start to poll if erase has been done.
Anyway this prove that upstreaming die erase impl. Is not good idea for now.
Let's wait for your JESD218 work to be merged.
>
> Then, if you make the whole memory enter its 4-byte address mode to erase
> one single die and a spurious reboot occurs, many bootloaders would fail to
> read the old firmware from the other die just because the whole memory
> expects 4-byte addresses.
>
> About the QPI mode (SPI 4-4-4), I agree with you, it has the very same
> annoying side effect. Hence I've removed support of the SPI 2-2-2 and SPI
> 4-4-4 protocols at the memory side from my SFDP series for the moment.
And that's remained me I have a comment about that :)
Thanks,
Marcin
> Besides, on the controller side, by changing the 3rd argument parameter of
> spi_nor_scan(), one of my patch allows the SPI controller driver to claim "I
> can't/don't want to use SPI 4-4-4 but I support SPI 1-1-4 and SPI 1-4-4
> protocols". So the SPI 4-4-4 protocol can be disabled if needed.
>
> Best regards,
>
> Cyrille
>
>
> > Thanks,
> > Marcin
> >
> >>
> >>>>
> >>>> Maybe I'm wrong but the assumption (multi-die => chip erase not
> >>>> supported) might be false.
> >>> It is false, but all multi-die chip I know support die erase or chip erase.
> >>> Never both.
> >>>
> >>> Thanks,
> >>> Marcin
> >>>
> >>>>
> >>>>
> >>>> Best regards,
> >>>>
> >>>> Cyrille
> >>>>
> >>>>
> >>>>>>
> >>>>>> Best regards,
> >>>>>>
> >>>>>> Cyrille
> >>>>>>
> >>>>>>> Signed-off-by: Marcin Krzeminski <marcin.krzeminski at nokia.com>
> >>>>>>> ---
> >>>>>>> drivers/mtd/spi-nor/spi-nor.c | 90
> >>>>>>> +++++++++++++++++++++++++++++++++++++------
> >>>>>>> 1 file changed, 78 insertions(+), 12 deletions(-)
> >>>>>>>
> >>>>>>> diff --git a/drivers/mtd/spi-nor/spi-nor.c
> >>>>>>> b/drivers/mtd/spi-nor/spi-nor.c index 3afe207..17bbec0 100644
> >>>>>>> --- a/drivers/mtd/spi-nor/spi-nor.c
> >>>>>>> +++ b/drivers/mtd/spi-nor/spi-nor.c
> >>>>>>> @@ -360,6 +360,29 @@ static int spi_nor_erase_sector(struct
> >>>>>>> spi_nor
> >>>>>> *nor, u32 addr)
> >>>>>>> return nor->write_reg(nor, nor->erase_opcode, buf, nor-
> >>>>>>> addr_width); }
> >>>>>>>
> >>>>>>> +static inline int spi_nor_sector_at_time_erase(struct mtd_info
> >>>>>>> +*mtd,
> >>>>>>> +u32 addr, u32 len) {
> >>>>>>> + struct spi_nor *nor = mtd_to_spi_nor(mtd);
> >>>>>>> + int ret = 0;
> >>>>>>> +
> >>>>>>> + while (len) {
> >>>>>>> + write_enable(nor);
> >>>>>>> +
> >>>>>>> + ret = spi_nor_erase_sector(nor, addr);
> >>>>>>> + if (ret)
> >>>>>>> + return ret;
> >>>>>>> +
> >>>>>>> + addr += mtd->erasesize;
> >>>>>>> + len -= mtd->erasesize;
> >>>>>>> +
> >>>>>>> + ret = spi_nor_wait_till_ready(nor);
> >>>>>>> + if (ret)
> >>>>>>> + return ret;
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + return ret;
> >>>>>>> +}
> >>>>>>> +
> >>>>>>> /*
> >>>>>>> * Erase an address range on the nor chip. The address range
> >>>>>>> may
> >>>> extend
> >>>>>>> * one or more erase sectors. Return an error is there is a
> >>>>>>> problem
> >>>> erasing.
> >>>>>>> @@ -367,9 +390,11 @@ static int spi_nor_erase_sector(struct
> >>>>>>> spi_nor *nor, u32 addr) static int spi_nor_erase(struct
> >>>>>>> mtd_info *mtd, struct erase_info *instr) {
> >>>>>>> struct spi_nor *nor = mtd_to_spi_nor(mtd);
> >>>>>>> - u32 addr, len;
> >>>>>>> + u32 addr, len, die_no, die_size;
> >>>>>>> uint32_t rem;
> >>>>>>> int ret;
> >>>>>>> + unsigned long timeout;
> >>>>>>> + u8 die_erase = nor->die_cnt && SNOR_F_DIE_ERASE;
> >>>>>>>
> >>>>>>> dev_dbg(nor->dev, "at 0x%llx, len %lld\n", (long long)instr-
> >addr,
> >>>>>>> (long long)instr->len);
> >>>>>>> @@ -386,7 +411,7 @@ static int spi_nor_erase(struct mtd_info
> >>>>>>> *mtd,
> >>>>>> struct erase_info *instr)
> >>>>>>> return ret;
> >>>>>>>
> >>>>>>> /* whole-chip erase? */
> >>>>>>> - if (len == mtd->size) {
> >>>>>>> + if (len == mtd->size && !die_erase) {
> >>>>>>> unsigned long timeout;
> >>>>>>>
> >>>>>>> write_enable(nor);
> >>>>>>> @@ -416,17 +441,58 @@ static int spi_nor_erase(struct mtd_info
> >>>>>>> *mtd, struct erase_info *instr)
> >>>>>>>
> >>>>>>> /* "sector"-at-a-time erase */
> >>>>>>> } else {
> >>>>>>> - while (len) {
> >>>>>>> - write_enable(nor);
> >>>>>>> -
> >>>>>>> - ret = spi_nor_erase_sector(nor, addr);
> >>>>>>> - if (ret)
> >>>>>>> + if (die_erase) {
> >>>>>>> + die_size = div_u64_rem(mtd->size, nor-
> >>> die_cnt,
> >>>>>> &rem);
> >>>>>>> + if (rem) {
> >>>>>>> + ret = -EINVAL;
> >>>>>>> goto erase_err;
> >>>>>>> -
> >>>>>>> - addr += mtd->erasesize;
> >>>>>>> - len -= mtd->erasesize;
> >>>>>>> -
> >>>>>>> - ret = spi_nor_wait_till_ready(nor);
> >>>>>>> + }
> >>>>>>> + while (len) {
> >>>>>>> + die_no = div_u64_rem(addr,
> >> die_size,
> >>>>>> &rem);
> >>>>>>> +
> >>>>>>> + /* Check if address is aligned to die
> >> begin*/
> >>>>>>> + if (!rem) {
> >>>>>>> + /* die erase? */
> >>>>>>> + if (len >= die_size) {
> >>>>>>> + ret =
> >> spi_nor_die_erase(nor,
> >>>>>> addr);
> >>>>>>> + if (ret)
> >>>>>>> + goto
> >> erase_err;
> >>>>>>> +
> >>>>>>> + len -= die_size;
> >>>>>>> + addr += die_size;
> >>>>>>> +
> >>>>>>> + timeout =
> >>>>>> max(CHIP_ERASE_2MB_READY_WAIT_JIFFIES,
> >>>>>>> +
> >>>>>> CHIP_ERASE_2MB_READY_WAIT_JIFFIES *
> >>>>>>> +
> >> (unsigned
> >>>>>> long)(die_size / SZ_2M));
> >>>>>>> + ret =
> >>>>>> spi_nor_wait_till_ready_with_timeout(nor, timeout);
> >>>>>>> + if (ret)
> >>>>>>> + goto
> >> erase_err;
> >>>>>>> + } else {
> >>>>>>> + ret =
> >>>>>> spi_nor_sector_at_time_erase(mtd, addr, len);
> >>>>>>> + if (ret)
> >>>>>>> + goto
> >> erase_err;
> >>>>>>> + len = 0;
> >>>>>>> + }
> >>>>>>> + } else {
> >>>>>>> + /* check if end address cover
> >> at least
> >>>>>> one die */
> >>>>>>> + if (div64_ul(addr + len,
> >> die_size) >
> >>>>>> ++die_no) {
> >>>>>>> + /* align to next die */
> >>>>>>> + rem = die_size - rem;
> >>>>>>> + ret =
> >>>>>> spi_nor_sector_at_time_erase(mtd, addr, rem);
> >>>>>>> + if (ret)
> >>>>>>> + goto
> >> erase_err;
> >>>>>>> + len -= rem;
> >>>>>>> + addr += rem;
> >>>>>>> + } else {
> >>>>>>> + ret =
> >>>>>> spi_nor_sector_at_time_erase(mtd, addr, len);
> >>>>>>> + if (ret)
> >>>>>>> + goto
> >> erase_err;
> >>>>>>> + len = 0;
> >>>>>>> + }
> >>>>>>> + }
> >>>>>>> + }
> >>>>>>> + } else {
> >>>>>>> + ret = spi_nor_sector_at_time_erase(mtd,
> >> addr, len);
> >>>>>>> if (ret)
> >>>>>>> goto erase_err;
> >>>>>>> }
> >>>>>>>
> >>>>>
> >>>>>
> >>>
> >>>
> >
> >
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