[PATCH v2 0/8] drm: make leftover drivers call drm_atomic_helper_shutdown() at the right times

[Douglas Anderson]

This patch series is the leftovers of a patch series sent in September
2023 [1] in an attempt to get some of the patches landed finally.

This patch series originally came about after a _long_ discussion
between me and Maxime Ripard in response to a different patch I sent
out [2]. As part of that discussion, we realized that it would be good
if DRM drivers consistently called drm_atomic_helper_shutdown()
properly at shutdown and driver remove time as it's documented that
they should do. The eventual goal of this would be to enable removing
some hacky code from panel drivers where they had to hook into
shutdown themselves because the DRM driver wasn't calling them.

It turns out that quite a lot of drivers seemed to be missing
drm_atomic_helper_shutdown() in one or both places that it was
supposed to be. This patch series attempts to fix all the drivers that
I was able to identify.

NOTE: fixing this wasn't exactly cookie cutter. Each driver has its
own unique way of setting itself up and tearing itself down. Some
drivers also use the component model, which adds extra fun. I've made
my best guess at solving this and I've run a bunch of compile tests
(specifically, allmodconfig for amd64, arm64, and powerpc). That being
said, these code changes are not totally trivial and I've done zero
real testing on them. Making these patches was also a little mind
numbing and I'm certain my eyes glazed over at several points when
writing them. What I'm trying to say is to please double-check that I
didn't do anything too silly, like cast your driver's drvdata to the
wrong type. Even better, test these patches!

Apparently most of these drivers now land through drm-misc [3], so
hopefully they can land. The two that don't (amdgpu and radeon) are
the ones I'm most ucertain about anyway so I've stuck them at the end.
If I've totally buggered those up feel free to take my patch as a bug
report and submit your own proper fix. ...or if there's some reason
that we don't need to do anything for those drivers then let me know
and we can drop them.

I'd like to call out a few drivers that I _didn't_ fix in this series
and why. If any of these drivers should be fixed then please yell.
- DRM drivers backed by usb_driver (like gud, gm12u320, udl): I didn't
  add the call to drm_atomic_helper_shutdown() at shutdown time
  because there's no ".shutdown" callback for them USB drivers. Given
  that USB is hotpluggable, I'm assuming that they are robust against
  this and the special shutdown callback isn't needed.
- ofdrm and simpledrm: These didn't have drm_atomic_helper_shutdown()
  in either shutdown or remove, but I didn't add it. I think that's OK
  since they're sorta special and not really directly controlling
  hardware power sequencing.
- virtio, vkms, vmwgfx, xen: I believe these are all virtual (thus
  they wouldn't directly drive a panel) and adding the shutdown
  didn't look straightforward, so I skipped them.

I've let each patch in the series get CCed straight from
get_maintainer. That means not everyone will have received every patch
but everyone should be on the cover letter. I know some people dislike
this but when touching this many drivers there's not much
choice. dri-devel and lkml have been CCed and lore/lei exist, so
hopefully that's enough for folks. I'm happy to add people to the
whole series for future posts.

[1] https://lore.kernel.org/r/20230901234202.566951-1-dianders@chromium.org
[2] https://lore.kernel.org/r/20230804140605.RFC.4.I930069a32baab6faf46d6b234f89613b5cec0f14@changeid
[3] https://lore.kernel.org/r/Zmm6_27GikpmT3HQ@phenom.ffwll.local

Changes in v2:
- Gathered whatever hadn't landed, rebased, and reposted.

Douglas Anderson (8):
  drm/kmb: Call drm_atomic_helper_shutdown() at shutdown time
  drm/nouveau: Call drm_atomic_helper_shutdown() or equiv at shutdown
    time
  drm/tegra: Call drm_atomic_helper_shutdown() at shutdown time
  drm/arcpgu: Call drm_atomic_helper_shutdown() at shutdown time
  drm/sprd: Call drm_atomic_helper_shutdown() at remove time
  drm/gma500: Call drm_helper_force_disable_all() at shutdown/remove
    time
  drm/radeon: Call drm_helper_force_disable_all() at shutdown/remove
    time
  drm/amdgpu: Call drm_atomic_helper_shutdown() at shutdown time

 drivers/gpu/drm/amd/amdgpu/amdgpu.h        |  1 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 10 ++++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    |  2 ++
 drivers/gpu/drm/gma500/psb_drv.c           |  8 ++++++++
 drivers/gpu/drm/kmb/kmb_drv.c              |  6 ++++++
 drivers/gpu/drm/nouveau/nouveau_display.c  |  9 +++++++++
 drivers/gpu/drm/nouveau/nouveau_display.h  |  1 +
 drivers/gpu/drm/nouveau/nouveau_drm.c      | 13 +++++++++++++
 drivers/gpu/drm/nouveau/nouveau_drv.h      |  1 +
 drivers/gpu/drm/nouveau/nouveau_platform.c |  6 ++++++
 drivers/gpu/drm/radeon/radeon_drv.c        |  7 ++++++-
 drivers/gpu/drm/sprd/sprd_drm.c            |  4 +++-
 drivers/gpu/drm/tegra/drm.c                |  6 ++++++
 drivers/gpu/drm/tiny/arcpgu.c              |  6 ++++++
 14 files changed, 78 insertions(+), 2 deletions(-)

-- 
2.45.2.505.gda0bf45e8d-goog