Barebox / Kernel Omap ECC inconsistency?

Barebox / Kernel Omap ECC inconsistency?

[Colin Foster]

Hello,

I'm trying to revive a product that runs on a Phytec OMAP 4460 SOM. I
submitted a .dts RFC a month or so ago, and plan to perform the
suggestions and resubmit, but I'm up against one main hurdle that seems
to be related to flash OOB/ECC. (get_maintainers on
drivers/mtd/nand/raw/omap2.c is how I got this email list)

Barebox has "native" support for the Phytec SOM:
https://git.pengutronix.de/cgit/barebox/tree/arch/arm/boards/phytec-phycore-omap4460

It seems like Barebox is writing and expecting ECC bits to start at an
offset of 12 bytes, while the kernel (and Barebox comments suggest) the
ECC bytes should start at 2. I'm seeing this with
`nanddump -n -o -l 0x41000 -f mtdxnanddump /dev/mtdx`

Barebox created partition with UBI (mtd3)
...
00000800  ff ff ff ff ff ff ff ff  ff ff ff ff 56 49 fd 17
00000810  b2 25 60 1a 42 1d eb 56  5d ff ff ff ff ff ff ff
...

Kernel created partition with UBI (mtd4)
...
00000800  ff ff 07 73 04 ac 57 6b  9b 1f 92 49 ab e0 b9 ff
00000810  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff
...


My question: 

Am I right to assume this is an issue in Barebox? Perhaps this is just a
bug that has been fairly dormant for 15 years. If that is the case, I
assume there's probably no hope in getting this mainlined, and "native"
barebox support is just a ruse.

If that isn't the case, is there a hidden "shift OOB by 10" config
option that I'm missing? Or am I interpreting this data incorrectly?


Any suggestions would be greatly appreciated.

Thanks,

Colin Foster

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Re: Barebox / Kernel Omap ECC inconsistency?

[Roger Quadros]

Hi Colin,

On 01/11/2022 21:09, Colin Foster wrote:
> Hello,
> 
> I'm trying to revive a product that runs on a Phytec OMAP 4460 SOM. I
> submitted a .dts RFC a month or so ago, and plan to perform the
> suggestions and resubmit, but I'm up against one main hurdle that seems
> to be related to flash OOB/ECC. (get_maintainers on
> drivers/mtd/nand/raw/omap2.c is how I got this email list)
> 
> Barebox has "native" support for the Phytec SOM:
> https://git.pengutronix.de/cgit/barebox/tree/arch/arm/boards/phytec-phycore-omap4460
> 
> It seems like Barebox is writing and expecting ECC bits to start at an
> offset of 12 bytes, while the kernel (and Barebox comments suggest) the
> ECC bytes should start at 2. I'm seeing this with
> `nanddump -n -o -l 0x41000 -f mtdxnanddump /dev/mtdx`
> 
> Barebox created partition with UBI (mtd3)
> ...
> 00000800  ff ff ff ff ff ff ff ff  ff ff ff ff 56 49 fd 17
> 00000810  b2 25 60 1a 42 1d eb 56  5d ff ff ff ff ff ff ff
> ...
> 
> Kernel created partition with UBI (mtd4)
> ...
> 00000800  ff ff 07 73 04 ac 57 6b  9b 1f 92 49 ab e0 b9 ff
> 00000810  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff
> ...
> 
> 
> My question: 
> 
> Am I right to assume this is an issue in Barebox? Perhaps this is just a

I'm guessing so. Both u-boot and Linux for OMAP put the ECC bytes right
after the Bad block marker which is 2 bytes.

https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/omap2.c#L1729
https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/omap2.c#L134

> bug that has been fairly dormant for 15 years. If that is the case, I
> assume there's probably no hope in getting this mainlined, and "native"
> barebox support is just a ruse.
> 
> If that isn't the case, is there a hidden "shift OOB by 10" config
> option that I'm missing? Or am I interpreting this data incorrectly?
> 
> 
> Any suggestions would be greatly appreciated.

You should fix the OMAP NAND driver/config in Barebox to match that
with Linux OMAP NAND driver if you want them to run on the same system.

cheers,
-roger

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Re: Barebox / Kernel Omap ECC inconsistency?

[Miquel Raynal]

Hi Colin,

rogerq@kernel.org wrote on Wed, 2 Nov 2022 09:12:27 +0200:

> Hi Colin,
> 
> On 01/11/2022 21:09, Colin Foster wrote:
> > Hello,
> > 
> > I'm trying to revive a product that runs on a Phytec OMAP 4460 SOM. I
> > submitted a .dts RFC a month or so ago, and plan to perform the
> > suggestions and resubmit, but I'm up against one main hurdle that seems
> > to be related to flash OOB/ECC. (get_maintainers on
> > drivers/mtd/nand/raw/omap2.c is how I got this email list)
> > 
> > Barebox has "native" support for the Phytec SOM:
> > https://git.pengutronix.de/cgit/barebox/tree/arch/arm/boards/phytec-phycore-omap4460
> > 
> > It seems like Barebox is writing and expecting ECC bits to start at an
> > offset of 12 bytes, while the kernel (and Barebox comments suggest) the
> > ECC bytes should start at 2. I'm seeing this with
> > `nanddump -n -o -l 0x41000 -f mtdxnanddump /dev/mtdx`
> > 
> > Barebox created partition with UBI (mtd3)
> > ...
> > 00000800  ff ff ff ff ff ff ff ff  ff ff ff ff 56 49 fd 17
> > 00000810  b2 25 60 1a 42 1d eb 56  5d ff ff ff ff ff ff ff
> > ...
> > 
> > Kernel created partition with UBI (mtd4)
> > ...
> > 00000800  ff ff 07 73 04 ac 57 6b  9b 1f 92 49 ab e0 b9 ff
> > 00000810  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff
> > ...
> > 
> > 
> > My question: 
> > 
> > Am I right to assume this is an issue in Barebox? Perhaps this is just a  
> 
> I'm guessing so. Both u-boot and Linux for OMAP put the ECC bytes right
> after the Bad block marker which is 2 bytes.

Yep. I checked, this has been like that since at least 2014, I don't
think we changed the layout in U-Boot/Linux "recently"... (I haven't
checked earlier, by laziness).

> https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/omap2.c#L1729
> https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/omap2.c#L134
> 
> > bug that has been fairly dormant for 15 years. If that is the case, I
> > assume there's probably no hope in getting this mainlined, and "native"
> > barebox support is just a ruse.
> > 
> > If that isn't the case, is there a hidden "shift OOB by 10" config
> > option that I'm missing? Or am I interpreting this data incorrectly?
> > 
> > 
> > Any suggestions would be greatly appreciated.  
> 
> You should fix the OMAP NAND driver/config in Barebox to match that
> with Linux OMAP NAND driver if you want them to run on the same system.

Agreed.

Thanks,
Miquèl

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Re: Barebox / Kernel Omap ECC inconsistency?

[Colin Foster]

On Wed, Nov 02, 2022 at 02:14:00PM +0100, Miquel Raynal wrote:
> Hi Colin,
> 
> rogerq@kernel.org wrote on Wed, 2 Nov 2022 09:12:27 +0200:
> 
> > Hi Colin,
> > 
> > On 01/11/2022 21:09, Colin Foster wrote:
> > > Hello,
> > > 
> > > I'm trying to revive a product that runs on a Phytec OMAP 4460 SOM. I
> > > submitted a .dts RFC a month or so ago, and plan to perform the
> > > suggestions and resubmit, but I'm up against one main hurdle that seems
> > > to be related to flash OOB/ECC. (get_maintainers on
> > > drivers/mtd/nand/raw/omap2.c is how I got this email list)
> > > 
> > > Barebox has "native" support for the Phytec SOM:
> > > https://git.pengutronix.de/cgit/barebox/tree/arch/arm/boards/phytec-phycore-omap4460
> > > 
> > > It seems like Barebox is writing and expecting ECC bits to start at an
> > > offset of 12 bytes, while the kernel (and Barebox comments suggest) the
> > > ECC bytes should start at 2. I'm seeing this with
> > > `nanddump -n -o -l 0x41000 -f mtdxnanddump /dev/mtdx`
> > > 
> > > Barebox created partition with UBI (mtd3)
> > > ...
> > > 00000800  ff ff ff ff ff ff ff ff  ff ff ff ff 56 49 fd 17
> > > 00000810  b2 25 60 1a 42 1d eb 56  5d ff ff ff ff ff ff ff
> > > ...
> > > 
> > > Kernel created partition with UBI (mtd4)
> > > ...
> > > 00000800  ff ff 07 73 04 ac 57 6b  9b 1f 92 49 ab e0 b9 ff
> > > 00000810  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff
> > > ...
> > > 
> > > 
> > > My question: 
> > > 
> > > Am I right to assume this is an issue in Barebox? Perhaps this is just a  
> > 
> > I'm guessing so. Both u-boot and Linux for OMAP put the ECC bytes right
> > after the Bad block marker which is 2 bytes.
> 
> Yep. I checked, this has been like that since at least 2014, I don't
> think we changed the layout in U-Boot/Linux "recently"... (I haven't
> checked earlier, by laziness).
> 
> > https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/omap2.c#L1729
> > https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/omap2.c#L134
> > 
> > > bug that has been fairly dormant for 15 years. If that is the case, I
> > > assume there's probably no hope in getting this mainlined, and "native"
> > > barebox support is just a ruse.
> > > 
> > > If that isn't the case, is there a hidden "shift OOB by 10" config
> > > option that I'm missing? Or am I interpreting this data incorrectly?
> > > 
> > > 
> > > Any suggestions would be greatly appreciated.  
> > 
> > You should fix the OMAP NAND driver/config in Barebox to match that
> > with Linux OMAP NAND driver if you want them to run on the same system.
> 
> Agreed.

Got it. Thanks a lot for the info Roger and Miquel. I think this should
be pretty doable, and I'll venture down that path.

> 
> Thanks,
> Miquèl

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