[PATCH v6 05/12] power-domain: Add refcounting

[Nishanth Menon]

On 23:06-20250414, Francis, Neha wrote:
> On 4/3/2025 1:09 PM, Miquel Raynal wrote:
> > 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 at bootlin.com>
> > ---
> 
> This commit looks to be breaking K3 platforms boot, please see "Latest Boot
> Summary" [0]. Reverting the commit fixes boot.
> 
> [0] https://lcpd.itg.ti.com/upstream/k3-boot-build/main/build-trends.html

Uggh. This link is a TI internal link. Nutshell, it is broken
between:
v2025.04-921-gcb7555e93075 : https://source.denx.de/u-boot/u-boot.git
and
v2025.04-1041-g407d68638fe3 : https://source.denx.de/u-boot/u-boot.git

Neha bisected it down to 197376fbf300e92afa0a1583815d9c9eb52d613a commit
which is this patch.

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D