Messages in this thread | | | From | Peter Pan 潘栋 (peterpandong) <> | Subject | RE: [PATCH 0/3] An alternative to SPI NAND | Date | Fri, 30 Jan 2015 00:57:25 +0000 |
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> On 01/20/2015 11:11 PM, Qi Wang 王起 (qiwang) wrote: > > On 01/20/2015 6:36 PM, Ezequiel Garcia wrote: > >> > >> On 01/12/2015 12:10 PM, Qi Wang 王起 (qiwang) wrote: > >>> Hi Ezequiel, > >>> > >>> On 01/08/2015 11:27 AM, Ezequiel Garcia wrote: > >>>> > >>>> Hi Qi Wang, > >>>> > >>>> On 01/07/2015 11:45 PM, Qi Wang 王起 (qiwang) wrote: > >>>>> Hi Brian, > >>>>> > >>>>> On Thu, Jan 08, 2015 at 9:03:24AM +0000, Brian Norris wrote: > >>>>>> > >>>>>> On Thu, Jan 08, 2015 at 12:47:24AM +0000, Peter Pan 潘栋 > (peterpandong) > >>>>>> wrote: > >>>>>>> Documentation/devicetree/bindings/mtd/spi-nand.txt | 22 + > >>>>>>> drivers/mtd/Kconfig | 2 + > >>>>>>> drivers/mtd/Makefile | 1 + > >>>>>>> drivers/mtd/spi-nand/Kconfig | 7 + > >>>>>>> drivers/mtd/spi-nand/Makefile | 3 + > >>>>>>> drivers/mtd/spi-nand/spi-nand-base.c | 2034 > >>>>>> ++++++++++++++++++++ > >>>>>>> drivers/mtd/spi-nand/spi-nand-bbt.c | 1279 > >> ++++++++++++ > >>>>>> > >>>>>> I can already tell by the diffstat that I don't like this. We > probably > >>>>>> don't need 3000 new lines of code for this, but we especially > don't > >> want > >>>>>> to duplicate nand_bbt.c. It won't take a lot of work to augment > >>>>>> nand_bbt.c to make it shareable. (I can whip that patch up if > needed.) > >>>>> > >>>>> Yes, I agree with you, Nand_bbt.c do can be shared by Parallel > NAND and > >>>>> SPI NAND. Actually, we are working at this now. Will send patches > to > >> you > >>>>> Once we finished it. > >>>>> > >>>> > >>>> Thanks for the quick submission! > >>>> > >>>> However, Brian is right, this code duplication is a no go. > >>>> > >>>> Perhaps a more valid approach would be to first identify the code > that > >>>> needs to be shared in nand_bbt.c and nand_base.c, and export those > >>>> symbols (or maybe do the required refactor). > >>> > >>> Yes, I agree Brian's suggestion in another mail. > >>> > >>> " The BBT code is something we definitely want to share, but it's > >> actually > >>> not very closely tied to nand_base.c, and it looks pretty easy to > adapt > >>> to any MTD that implements mtd_read_oob()/mtd_write_oob(). We'd > just > >>> need to parameterize a few relevant device details into a new > nand_bbt > >>> struct, rather than using struct nand_chip directly." > >>> > >>> To abstract a new nand_bbt struct instead of nand_chip to make SPI > NAND > >>> and parallel NAND can share nand_bbt.c file, I already begin to > work on > >>> this. > >>> > >>> For code shared in nand_base.c, I agree it would be better if we > can find > >>> a good method to share nand_base.c code between spi nand and > parallel > >> nand. > >>> But frankly speaking, I'm not satisfied for the remap command > method. > >> This > >>> method make code difficult to maintain when SPI NAND and Parallel > NAND > >>> evolve much differently in the future. > >>> > >>> Take some example, > >>> If one new command (cache operation, multiple plane operation) > >> implemented > >>> in parallel NAND code, and is used in nand_read or nand_write, that > will > >>> cause maintainer to modify SPI NAND code to remap this new command, > >> though > >>> this modification probably could be slight. That means modification > on > >>> Parallel NAND flash need to consider SPI NAND as well. > >>> > >>> How do you think about this? > >>> > >>> For Peter Pan's patchset, if we do some modification to make > nand_bbt.c > >> to > >>> make it shareable for Parallel and SPI NAND. The code line should > be 2000. > >>> I believe I can review this spi-nand-base.c to remove some > redundant code > >>> that may hundreds line. Is 1700 or 1800 code line is more > acceptable? > >>> > >>> Let me know your opinions. > >>> > >> > >> Sounds good. > >> > >> Do you still plan to maintain the spi-nand-base.c and spi-nand- > device.c > >> separation? > > > > Yes, still plan to maintain the spi-nand-base.c and spi-nand-device.c > > separation. Abstract common code to spi-nand-base.c, and spi-nand- > device.c is > > used for realize the different function for different SPI NAND, such > as ecc > > layout, read ID etc. > > > > Any news about this? Is there anything I can do to help (reviewing, > testing, coding...)? > > Thanks! > -- > Ezequiel
Currently, we are working on sharing the bbt code. I think your and Brain's suggestion will be very helpful.
There are two options. We can put struct nand_bbt pointer in either nand_chip or mtd_info structure. If put nand_bbt in nand_chip, we need to change the parameter of nand_chip->scan_bbt function from mtd_info to nand_bbt. But nand_chip->scan_bbt is used in many place. drivers/mtd/nand/diskonchip.c:1372: this->scan_bbt = nftl_scan_bbt; drivers/mtd/nand/diskonchip.c:1399: this->scan_bbt = inftl_scan_bbt; drivers/mtd/nand/diskonchip.c:1405: this->scan_bbt = nftl_scan_bbt; drivers/mtd/nand/diskonchip.c:1418: this->scan_bbt = inftl_scan_bbt; drivers/mtd/nand/nand_base.c:2986: if (!chip->scan_bbt) drivers/mtd/nand/nand_base.c:2987: chip->scan_bbt = nand_default_bbt; drivers/mtd/nand/nand_base.c:4159: * Initialize bitflip_threshold to its default prior scan_bbt() call. drivers/mtd/nand/nand_base.c:4160: * scan_bbt() might invoke mtd_read(), thus bitflip_threshold must be drivers/mtd/nand/nand_base.c:4171: return chip->scan_bbt(mtd); drivers/mtd/nand/gpmi-nand/gpmi-nand.c:1953: chip->scan_bbt(mtd); drivers/mtd/nand/docg4.c:1083: * first page of the block. The default scan_bbt() in the nand drivers/mtd/nand/nandsim.c:2381: if ((retval = chip->scan_bbt(nsmtd)) != 0) drivers/mtd/onenand/onenand_base.c:3976: if (!this->scan_bbt) drivers/mtd/onenand/onenand_base.c:3977: this->scan_bbt = onenand_default_bbt; drivers/mtd/onenand/onenand_base.c:4101: ret = this->scan_bbt(mtd); If put nand_bbt in mtd_info, we needn't to change the parameter of nand_chip->scan_bbt. But only nand flash need bbt, I don't know whether it is proper to put nand_bbt structure in mtd_info or not.
Besides, using nand_bbt struct will cause some elements(such as chip_size, page_size and so on) in both nand_chip and nand_bbt struct.
Maybe there is another way but I don't know. So please feel free to talk about it.
Brain, could you give some suggestion ? We really need your help.
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