ath79: add mikrotik subtarget

[rogerpueyo]

This is a RFC for adding a new ath79/mikrotik subtarget and moving the two currently supported MikroTik devices there. The main rationale behind this is the need for:

• CONFIG_MTD_SPI_NOR_USE_4K_SECTORS=y to property to manage the 4K-sized flash partitions
• FEATURES += minor and CONFIG_MTD_SPLIT_MINOR_FW=y for the MiNor (MikroTik NOR) split MTD format

Issues (so far):

• mikrotik/config-default has the symbols from ath79/generic + ath79/nand + ar71xx/mikrotik, removing those that didn't seem needed (e.g. drivers not used). Are all of the current ones needed or is any missing?
• the NAND board (rb922) still has the BOARD_NAME variable (related: ath79: get rid of BOARD_NAME for RouterBOARD 922UAGS-5HPacD #2790)
• filenames get a duplicate "mikrotik" string, for the subtarget and for the vendor (e.g., openwrt-ath79-mikrotik-mikrotik_routerboard-922uags-5hpacd-squashfs-sysupgrade.bin)

---

This commit creates the ath79/mikrotik subtarget in order to support
MikroTik devices based on Qualcomm Atheros MIPS SoCs.

MikroTik devices need a couple of specific features: the split MiNOR
firmware MTD format, which is not used by other devices, and the 4k
sector erase size on SPI NOR storage, which can not be added to the
ath79/generic and ath79/nand subtargets now.

Additionally, the commit moves the two MikroTik devices already in
the generic and nand subtargets to this new one.

Tested on the RB922 board and the wAP AC router.

[adschm]

Since IIRC there was no response at all on this subject, let's just go on with this as the subtarget seems (unfortunately) the best solution for now.

I will have a closer look on the code later.

filenames get a duplicate "mikrotik" string, for the subtarget and for the vendor (e.g., openwrt-ath79-mikrotik-mikrotik_routerboard-922uags-5hpacd-squashfs-sysupgrade.bin)

Yes, that's not nice, but I'd still keep it for consistency.

When we added the first mikrotik device to ath79, I had the idea to call the subtarget "minor" instead of "mikrotik", but I'm not sure yet whether this is really an improvement for the entire situation.

[adschm]

@xback Can you check the symbols in new config-default for mikrotik target

[rogerpueyo]

Thanks, Adrian. :)

When we added the first mikrotik device to ath79, I had the idea to call the subtarget "minor" instead of "mikrotik", but I'm not sure yet whether this is really an improvement for the entire situation.

Yup, mikrotik_mikrotik is not nice, but is consistent. "minor" makes sense since the subtarget has the MiNor-type MTD, but it might be mistakenly understood by something in between "generic" and "tiny", who knows.

[adschm]

Looks good despite my comments and the config-default files where I would rely on @xback for judgement.

Your comment about the possible "minor" misunderstanding complements my other concerns, so let's just stay with mikrotik.

[adschm]

I've decided to merge this now as it somehow blocks development for mikrotik on ath79.
If we need to adjust kernel config afterwards, that should be easy to do ...

[rogerpueyo]

Great!

[ch6574]

Should this PR now mean we get snapshots appearing in https://downloads.openwrt.org/snapshots/targets/ath79/mikrotik/ ?

[f00b4r0]

The subtarget isn't autobuilt yet. Given it seems there is a problem with the handling of the soft_config partition erasesize, I recommend it remains that way for a bit longer to prevent "average users" from risking to trash their flash. I'm trying to isolate this regression.

[f00b4r0]

A bit of extra info, I think I spotted part of the problem (re erasesize issues): http://git.openwrt.org/9261e7447

I'm still investigating, it would also seem that 4K_SECTORS_LIMIT is also broken in 4.19

For now the ramips and ar71xx mikrotik devices are unaffected since they still run 4.14, in which the bug(s) is/are absent