Re: [PATCH v1 0/3] fdt: Fix mtparts fixup

[Tom Rini <trini@konsulko.com>]

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On Thu, Feb 23, 2023 at 11:23:41AM +0100, Patrick DELAUNAY wrote:
> Hi,
> 
> On 1/23/23 21:01, Tom Rini wrote:
> > On Mon, Jan 23, 2023 at 11:06:06AM +0100, Miquel Raynal wrote:
> > > Hi Tom,
> > > 
> > > trini@konsulko.com wrote on Fri, 13 Jan 2023 14:34:11 -0500:
> > > 
> > > > On Fri, Jan 13, 2023 at 07:45:44PM +0100, Francesco Dolcini wrote:
> > > > 
> > > > > From: Francesco Dolcini <francesco.dolcini@toradex.com>
> > > > > 
> > > > > Recently we had a boot regression on colibri-imx7 because of a cleanup change
> > > > > on Linux imx7.dtsi setting nand controller node #size-cells from 1 to 0.
> > > > > 
> > > > > Because of that Linux partition parser was no longer able to properly
> > > > > parse the OF partitions leading to a boot failure, the above change was
> > > > > reverted in the meantime as an immediate workaround, but some improvement
> > > > > is required on both Linux and U-Boot.
> > > > > 
> > > > > This change improve the U-Boot part of it, #size-cell is set to 1 when
> > > > > it has an invalid value. This has the limitation to work only with devices
> > > > > smaller than 4GiB. In general the suggestion from the Linux MTD maintainer would
> > > > > be to just deprecate using this U-Boot function and pass the MTD partitions
> > > > > from the command line, unless they are statically defined in the DTS file
> > > > > in the first place.
> > > > > 
> > > > > This series therefore convert colibri-imx6ull and colibri-imx7 to pass the
> > > > > partition list from the command line instead of fixing up the DT.
> > > > > 
> > > > > Link: https://lore.kernel.org/all/20221202071900.1143950-1-francesco@dolcini.it/
> > > > > Link: https://lore.kernel.org/all/Y4dgBTGNWpM6SQXI@francesco-nb.int.toradex.com/
> > > > My higher level question / concern here is, is using one of the dts
> > > > partition schemes still valid / preferred, or should everyone now have
> > > > reverted to passing via the kernel command line?  If device tree still,
> > > > is mtd/partitions/fixed-partitions.yaml the one to follow or something
> > > > else?
> > > I don't think we can "prefer" one mode over the other between cmdline
> > > and DTS. Both should work pretty well. Of course on the cmdline you can
> > > only define fixed partitions and many devices require more advanced
> > > parsers, which are only available through DTS, but for simple
> > > partitions, it works totally okay.
> > When both are present, which one is used?
> > 
> > > The only thing that I would like to avoid is the need to write code in
> > > the bootloaders to tweak the FDT in order to add partitions. That is
> > > clearly not needed, error prone, and do not follow evolution of the
> > > "standard", as we just discovered.
> > I'm not sure about this. Looking around in U-Boot today, I see two types
> > of cases. One of which, the colibri case, can clearly be not done and
> > either passed on the command line, or put in to the device tree as
> > there's nothing run-time related being tweaked here. That's a fine path
> > to take on those platforms and Francesco's patches should be updated to
> > remove the unused C code too from the board code.
> > 
> > But the other cases are doing something dynamic and run-time related.
> > There's the omap3 igep00x0 family (which yes, legacy) that is doing NAND
> > or oneNAND and adjusting things at run time.  I don't know how much
> > anyone has interest in those platforms at this point, nor exactly who to
> > contact (for Linux or U-Boot). There's also the stm32mp1 family doing
> > something that's very not obvious at first glance, so I've cc'd the
> > maintainers there.
> > 
> 
> For information, today for stm32mp1 family we are using the build
> 
>  of MTDPARTS and fdt fixup, only for backward compatibility issue
> 
> (the MTD partitions change for boot with or without OP-TEE,
> 
> with or wihtout FIP, with SPL).
> 
> 
> Today we are already plan to remove this dynamic management
> 
> and to switch to static MTD partition defined in device tree,
> 
> as already proposed by Tom in the serie
> 
>  "mtd: spi: nor: force mtd name to "nor%d""
> 
> http://patchwork.ozlabs.org/project/uboot/patch/20210916155040.v3.2.Ia461e670c7438478aa8f8939209d45c818ccd284@changeid/
> 
> 
> This patchset is already ready, we are currently testing it internally
> 
> and it should be pushed when it will be validated in our donwstream.

Great, thanks.

-- 
Tom

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