tree a8d1e6aef4048a6973ea53f089d20814a7821ee4
parent 3b548d649e716b0a82adfc54b9f87bf3ecb27f06
author Miquel Raynal <miquel.raynal@bootlin.com> 1743665945 +0200
committer Fabio Estevam <festevam@gmail.com> 1744335175 -0300

power-domain: Add refcounting

It is very surprising that such an uclass, specifically designed to
handle resources that may be shared by different devices, is not keeping
the count of the number of times a power domain has been
enabled/disabled to avoid shutting it down unexpectedly or disabling it
several times.

Doing this causes troubles on eg. i.MX8MP because disabling power
domains can be done in recursive loops were the same power domain
disabled up to 4 times in a row. PGCs seem to have tight FSM internal
timings to respect and it is easy to produce a race condition that puts
the power domains in an unstable state, leading to ADB400 errors and
later crashes in Linux.

CI tests using power domains are slightly updated to make sure the count
of on/off calls is even and the results match what we *now* expect.

As we do not want to break existing users while stile getting
interesting error codes, the implementation is split between:
- a low-level helper reporting error codes if the requested transition
  could not be operated,
- a higher-level helper ignoring the "non error" codes, like EALREADY and
  EBUSY.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>