Messages in this thread | | | Date | Fri, 15 Oct 2021 10:20:09 +0200 | Subject | Re: nvmem: Defining cells on mtd created by mtdparts | From | Rafał Miłecki <> |
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On 11.10.2021 09:06, Sven Eckelmann wrote: > On Sunday, 10 October 2021 14:53:13 CEST Sven Eckelmann wrote: > [...] >> Since there are most likely more devices out there which use mtdparts, I would >> guess that there might already be a strategy out there which can be used to >> define the nvmem-provider for mtdparts defined partitions. At least I saw that >> Bartosz Golaszewski added all the mtd devices automatically as nvmem provider >> in c4dfa25ab307 ("mtd: add support for reading MTD devices via the nvmem >> API"). So there might also be something for nvmem-cells to find the correct >> mtd instead of relying on the fixed-partitions registration + of_node (which >> doesn't exist because it comes from mtdparts and not devicetree). > > Ansuel Smith just proposed in OpenWrt [1] a workaround. It basically adds a > minimal fixed-partitions parser to the mtd cmdlinepart parser (responsible for > the mtdparts=) that tries to find the matching (size + offset) fixed-partition > from the devicetree. The code in mtd_device_parse_register > (add_mtd_partitions -> add_mtd_device -> mtd_nvmem_add) will then > automatically take care of the rest.
I like the idea of connecting cmdline specified partitions (mtdparts=) with DT. That will help devices that use DT at least.
One thing I'm not sure about is criteria. Ansuel in his patch [PATCH] drivers: mtd: parsers: add nvmem support to cmdlinepart https://gist.github.com/Ansuel/35abba1f5663ea3d9bd8eded01e8d95b requires a matching name, offset & size.
I guess above may work for partitions that stay static like a bootloader. What if someone wants to describe more dynamic partition (firmware?). Should we reduce criteria to allow matching just by a name?
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