[U-Boot] [PATCH 3/3] doc: imx: Add documentation for nandbcb command

[Shyam Saini]

> On Tue, 18 Jun 2019 13:27:13 +0530
> Shyam Saini <shyam.saini at amarulasolutions.com> wrote:
>
> > Hi Lukasz,
> >
> >
> > > Hi Shyam,
> > >
> > > > Signed-off-by: Shyam Saini <shyam.saini at amarulasolutions.com>
> > > > ---
> > > >  doc/imx/common/imx6.txt | 74
> > > > +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed,
> > > > 74 insertions(+)
> > > >
> > > > diff --git a/doc/imx/common/imx6.txt b/doc/imx/common/imx6.txt
> > > > index eab88353f6..0b5061128c 100644
> > > > --- a/doc/imx/common/imx6.txt
> > > > +++ b/doc/imx/common/imx6.txt
> > > > @@ -88,3 +88,77 @@ Reading bank 4:
> > > >
> > > >  Word 0x00000002: 9f027772 00000004
> > > >
> > > > +NAND Boot on i.MX6 with SPL support
> > > > +--------------------------------------
> > > > +
> > > > +Writing/updating boot image in nand device is not straight
> > > > forward in +i.MX6 platform and it requires boot control
> > > > block(BCB) to be configured. +
> > > > +BCB contains two data structures, Firmware Configuration
> > > > Block(FCB) and +Discovered Bad Block Table(DBBT). FCB has nand
> > > > timings, DBBT search area, +and firmware. See IMX6DQRM Section
> > > > 8.5.2.2 +for more information.
> > > > +
> > > > +We can't use 'nand write' command to write SPL/firmware image
> > > > directly +like other platforms does. So we need special setup to
> > > > write BCB block +as per IMX6QDL reference manual 'nandbcb update'
> > > > command do that job. +
> > > > +for nand boot, up on reset bootrom look for FCB structure in
> > > > +first block's if FCB found the nand timings are loaded for
> > > > +further reads. once FCB read done, DTTB will be loaded and
> > > > +finally firmware will be loaded which is boot image.
> > > > +
> > > > +cmd_nandbcb will create FCB these structures
> > > > +by taking mtd partition as an example.
> > >
> > > I think that the above sentence has a wrong order. Could you
> > > rewrite it?
> > I'll fix this in next version.
> >
> > >
> > > > +- initial code will erase entire partition
> > > > +- followed by FCB setup, like first 2 blocks for FCB/DBBT write,
> > > > +  and next block for FW1/SPL
> > > > +- write firmware at FW1 block and
> > > > +- finally write fcb/dttb in first 2 block.
> > > > +
> > > > +Typical NAND BCB layout:
> > > > +=======================
> > > > +
> > > > +   no.of blocks = partition size / erasesize
> > > > +   no.of fcb/dbbt blocks = 2
> > > > +   FW1 offset = no.of fcb/dbbt
> > > > +
> > > > +block  0          1          2
> > > > +        -------------------------------
> > > > +       |FCB/DBBT 0|FCB/DBBT 1|  FW 1  |
> > > > +       --------------------------------
> > > > +
> > > > +On summary, nandbcb update will
> > > > +- erase the entire partition
> > > > +- create BCB by creating 2 FCB/BDDT block followed by
> > > > +  1 FW blocks based on partition size and erasesize.
> > > > +- fill FCB/DBBT structures
> > > > +- write FW/SPL in FW1
> > > > +- write FCB/DBBT in first 2 blocks
> > > > +
> > > > +step-1: write SPL
> > > > +
> > > > +icorem6qdl> ext4load mmc 0:1 $loadaddr SPL
> > > > +39936 bytes read in 10 ms (3.8 MiB/s)
> > > > +
> > > > +icorem6qdl> nandbcb update $loadaddr spl $filesize
> > > > +device 0 offset 0x0, size 0x9c00
> > > > +Erasing at 0x1c0000 -- 100% complete.
> > > > +NAND fw write: 0x80000 offset, 0xb000 bytes written: OK
> > > > +
> > > > +step-2: write u-boot-dtb.img
> > > > +
> > > > +icorem6qdl> nand erase.part uboot
> > > > +
> > > > +NAND erase.part: device 0 offset 0x200000, size 0x200000
> > > > +Erasing at 0x3c0000 -- 100% complete.
> > > > +OK
> > > > +
> > > > +icorem6qdl> ext4load mmc 0:1 $loadaddr u-boot-dtb.img
> > > > +589094 bytes read in 37 ms (15.2 MiB/s)
> > > > +
> > > > +icorem6qdl> nand write ${loadaddr} uboot ${filesize}
> > > > +
> > > > +NAND write: device 0 offset 0x200000, size 0x8fd26
> > > > + 589094 bytes written: OK
> > > > +icorem6qdl>
> > >
> > > Would it be possible to provide nandbcb show command (I guess that I
> > > can dump it with plain nand read)?
> >
> > As of now, fcb/dbbt structure are set only with nandbcb command
> > so before "nand info" we have to run nandbcb atleast once.
> >
> > If we consider kobs-ng in linux it prints fcb content when we write
> > some image so it means fcb is already populated at that time.
> >
> > > It would present the FCB/DBBT structure. Do you think it is
> > > needed/feasible ?
> >
> > Not sure if is it needed or not
> > if you have any proposal or suggestion about this then please let me
> > know.
>
> The idea/use case which I do think of is as follows:
>
> 1. I do receive a board with BCB written by bootloader from board
> vendor. It has parameters to configure the nand
>
> 2. I do use some command to read those parameters - to avoid situation
> that I lost them after first update (nand dump shall do the trick +
> hexeditor). Those parameters would be presented in a form easier to
> read/store than ones from hexeditor
>
> 3. I use nandbcb command to store those values read previously.

okay, it means simply printing fcb structure elements no matter it is
populated or not.
Is this you are suggesting ?

>
> >
> > Thanks a lot,
> > Shyam
> >
> >
> >
> >
> >
> > > Best regards,
> > >
> > > Lukasz Majewski
> > >
> > > --
> > >
> > > DENX Software Engineering GmbH,      Managing Director: Wolfgang
> > > Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell,
> > > Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> > > lukma at denx.de
>
>
>
>
> Best regards,
>
> Lukasz Majewski
>
> --
>
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de