[PATCH] drm/amdgpu: don't runtime suspend if there are displays attached (v2)

[Thorsten Leemhuis]

On 21.04.22 05:16, Alex Deucher wrote:
> We normally runtime suspend when there are displays attached if they
> are in the DPMS off state, however, if something wakes the GPU
> we send a hotplug event on resume (in case any displays were connected
> while the GPU was in suspend) which can cause userspace to light
> up the displays again soon after they were turned off.
> 
> Prior to
> commit 087451f372bf76 ("drm/amdgpu: use generic fb helpers instead of setting up AMD own's."),
> the driver took a runtime pm reference when the fbdev emulation was
> enabled because we didn't implement proper shadowing support for
> vram access when the device was off so the device never runtime
> suspended when there was a console bound.  Once that commit landed,
> we now utilize the core fb helper implementation which properly
> handles the emulation, so runtime pm now suspends in cases where it did
> not before.  Ultimately, we need to sort out why runtime suspend in not
> working in this case for some users, but this should restore similar
> behavior to before.
> 
> v2: move check into runtime_suspend
> v3: wake ups -> wakeups in comment, retain pm_runtime behavior in
>     runtime_idle callback
> 
> Fixes: 087451f372bf76 ("drm/amdgpu: use generic fb helpers instead of setting up AMD own's.")
> Tested-by: Michele Ballabio <ballabio.m at gmail.com>
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> [...]

Hi Alex, how can I bribe you to start placing "Link:" tags in
submissions that fix regressions (like this one), as explained in the
Linux kernels documentation (see
'Documentation/process/submitting-patches.rst' and
'Documentation/process/5.Posting.rst'). E.g. in this case like this:

"Link:
https://lore.kernel.org/r/20220403132322.51c90903@darkstar.example.org/"

This concept is not new (Linus and quite a few other developers use them
like this for a long time), I just recently improved those documents to
clarify things, as my regression tracking efforts rely on them -- that's
why it's making my work a lot harder if they are missing most of the
time. :-/

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)

P.S.: As the Linux kernel's regression tracker I'm getting a lot of
reports on my table. I can only look briefly into most of them and lack
knowledge about most of the areas they concern. I thus unfortunately
will sometimes get things wrong or miss something important. I hope
that's not the case here; if you think it is, don't hesitate to tell me
in a public reply, it's in everyone's interest to set the public record
straight.

#regzbot ^backmonitor:
https://lore.kernel.org/lkml/20220403132322.51c90903@darkstar.example.org/