On 9/25/21 2:12 AM, Marek Behún wrote:
On Fri, 24 Sep 2021 22:09:15 +0200
Marek Vasut <ma...@denx.de> wrote:
I have a feeling the discussion is again banking toward "mtdparts" and
"DT", which really is a solved problem, or at least we agreed upon the
solution.
I was trying to explain to Patrick how he can convert the ST board so
that the mtd partitions will be defined in DT and board code won't need
mtdids if he also converts to distro boot correctly.
The patch is trying to fix MTDIDS and their look up in
get_mtd_device_nm(). This is all U-Boot stuff, it has nothing to do with
passing mtd partitions to Linux at all.
The solution here is to get rid of MTDIDS also. But I guess this will
take some time, so it does make sense for get_mtd_device_nm() to
return the same device as previously when given argument "norN".
I'd say MTDIDS is user ABI, so we shouldn't break it until there is
clear way forward. (yes, I agree with pretty much all you are saying, I
just want to make this clear)
The reason why I put SPI NOR name into mtd->name was because otherwise
the `mtd list` command did not print that name anywhere (since it
doesn't know how, because that SPI-NOR data are private for the
jedec_spi_nor driver).
Since
- every mtd device has mtd->type, for NOR flash this is MTD_NORFLASH
- we can iterate mtd devices in order they were registered
(mtd_for_each_device does this)
we can easily implement a function
get_mtd_device_by_type_and_id()
No, we cannot. We have to make sure the Parallel NORs go first, SPI NORs
second, otherwise we break the old ABI. That's what Patrick is valiantly
battling here.
that, when given string "norN" will find the N-th mtd device of type
MTD_NORFLASH.
This function could than be called from get_mtd_device_nm() if
everything failed, or in some other way.
Tom, Marek, Patrick, what do you think?
Maybe we should go with a simpler counting approach first (at least for
this release) and then improve on that ? That would give us some time to
think the solution through ... at which point I wouldn't even be opposed
to passing full DT path to ubi part, something like:
ubi part /soc/controller@0x1234/flash@0/partition@1
or something like that. The above is always stable and unique because it
is hardware path, it does get flushed right down to get_mtd_device_nm(),
and it basically skips MTDIDS. With DT aliases you can probably write
some shorthand for a long HW path.
