Remove LNDMC_ALT_MAX

[MaEtUgR]

Solved Problem

When discussing with @sfuhrer about geofence improvements he mentioned again the overlap between LNDMC_ALT_MAX and GF_MAX_VER_DIST. I know @dagar was bringing this up many times.

I think now is the right time to remove it since I'm not aware who is using that functionality right now and @sfuhrer is working on geofence improvements which should allow us to forward users to using GF_MAX_VER_DIST.

Fixes #13345

Solution

I remove LNDMC_ALT_MAX completely.
It was introduced here: #6679
extended to shift down mission items here: #8048

Changelog Entry

Cleanup: Remove LNDMC_ALT_MAX, use GF_MAX_VER_DIST instead

Alternatives

We could use GF_MAX_VER_DIST in place of how LNDMC_ALT_MAX is currently used but:

• On multicopter it prevents breaching the altitude in any climb rate enabled mode which we should achieve with the geofence.
• On any vehicle, all mission items just get silently repositioned to be lower which was a hack to still allow RTL even if the return altitude is higher than the allowed altitude but flying lower than planned is not generally a safe thing to do. The check for the return altitude being lower than the maximum altitude should be done explicitly.

Test coverage

I did not specifically test this but the functionality was removed and it still compiles.

[sfuhrer]

For me this is a second implementation of a geofence feature, and thus support its removal.
If manufacturers want to implement a hard altitude limit that the user cannot overwrite then they can set GF_MAX_VER_DIST and GF_ACTION and do not give the user the ability to change them.

[sfuhrer]

Note: this would require a docs update (remove deprecated param).

[MaEtUgR]

this would require a docs update

It was actually never documented explicitly but only in the autogenerated reference 😅