Re: Proposal: U-Boot MTD (rewriting old story)

[Tom Rini <trini@konsulko.com>]

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On Wed, Aug 04, 2021 at 10:09:55AM -0600, Simon Glass wrote:
> Hi Jagan,
> 
> On Tue, 3 Aug 2021 at 09:01, Jagan Teki <jagan@amarulasolutions.com> wrote:
> >
> > Yes, this is the old discussion and triggered again now since we had a
> > discussion on the last U-Boot contributor call.
> >
> > I will brief the main points here, as most of the details are
> > mentioned in previous threads.
> >
> > Here are the couple of old and new implementations on the SPI-NOR side.
> >
> > http://u-boot.10912.n7.nabble.com/PATCH-v10-00-27-dm-Generic-MTD-Subsystem-with-SPI-NOR-interface-tt315694.html#none
> > http://u-boot.10912.n7.nabble.com/PATCH-0-5-mtd-Implement-MTD-UCLASS-use-SPINOR-td419538.html#a419541
> > https://patchwork.ozlabs.org/project/uboot/cover/20200709111709.68904-1-jagan@amarulasolutions.com/
> >
> > Idea is to
> > 1. Create MTD_UCLASS, already present
> > 2. Create DM MTD Operations, above patchset does.
> > 3. Create Flash specific MTD UClass's like
> >     UCLASS_NAND
> >     UCLASS_SPI_NAND
> >     UCLASS_SPI_NOR
> >     UCLASS_NOR
> >     UCLASS_UBI
> > and register to UCLASS_MTD as interface slaves like how MMC, SCSI are
> > registered to UCLASS_BLK
> > 4. Sync only respective flash specific code, and drop __UBOOT__
> > 5. Interface mtd, sf, and nand commands to UCLASS_MTD.
> 
> This all seems good to me.
> 
> >
> > Hard points:
> > 1. Hard to arrange Linux specific code and drop unneeded _UBOOT_ code,
> > but possible.
> > 2. Requires a lot of testing.
> 
> Let's add simple emulators for NAND, SPI_NAND and UBI. We already have
> one for SPI_NOR I believe. That will be a good long-term investment.

What are our viable options here via QEMU?

-- 
Tom

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