Nouveau - Sep 2023 - [RFT PATCH v2 00/12] drm: call drm_atomic_helper_shutdown() at the right times

This patch series came about after a _long_ discussion between me and
Maxime Ripard in response to a different patch I sent out [1]. 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!

I've labeled this patch series as RFT (request for testing) to help
call attention to the fact that I didn't personally test any of these
patches.

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.

NOTE: I landed everything I could from v1 of the patch series [2] [3]
to drm-misc. This v2 is everyone that is still left. If you'd like me
to land one of the patches here to drm-misc for you, please say
so. Otherwise I will assume maintainers will pick patches for their
particular driver and land them. There are no dependencies.

[1]
https://lore.kernel.org/lkml/20230804140605.RFC.4.I930069a32baab6faf46d6b234f89613b5cec0f14
at changeid
[2] https://lore.kernel.org/r/20230901234015.566018-1-dianders at chromium.org
[3] https://lore.kernel.org/r/20230901234202.566951-1-dianders at chromium.org

Changes in v2:
- Rebased and resolved conflicts.

Douglas Anderson (12):
  drm/imx/dcss: Call drm_atomic_helper_shutdown() at shutdown time
  drm/kmb: Call drm_atomic_helper_shutdown() at shutdown time
  drm/mediatek: 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/amdgpu: Call drm_atomic_helper_shutdown() at shutdown time
  drm/sprd: Call drm_atomic_helper_shutdown() at remove time
  drm/exynos: Call drm_atomic_helper_shutdown() at shutdown/unbind 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/renesas/shmobile: Call drm_helper_force_disable_all() at
    shutdown/remove 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/exynos/exynos_drm_drv.c          | 11 +++++++++++
 drivers/gpu/drm/gma500/psb_drv.c                 |  8 ++++++++
 drivers/gpu/drm/imx/dcss/dcss-drv.c              |  8 ++++++++
 drivers/gpu/drm/imx/dcss/dcss-kms.c              |  7 +++++++
 drivers/gpu/drm/imx/dcss/dcss-kms.h              |  1 +
 drivers/gpu/drm/kmb/kmb_drv.c                    |  6 ++++++
 drivers/gpu/drm/mediatek/mtk_drm_drv.c           |  9 +++++++++
 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/renesas/shmobile/shmob_drm_drv.c | 10 ++++++++++
 drivers/gpu/drm/sprd/sprd_drm.c                  |  4 +++-
 drivers/gpu/drm/tegra/drm.c                      |  6 ++++++
 drivers/gpu/drm/tiny/arcpgu.c                    |  6 ++++++
 20 files changed, 124 insertions(+), 2 deletions(-)

-- 
2.42.0.515.g380fc7ccd1-goog

Based on grepping through the source code this driver appears to be
missing a call to drm_atomic_helper_shutdown() (or
drm_helper_force_disable_all() if not using atomic) at system shutdown
time. Among other things, this means that if a panel is in use that it
won't be cleanly powered off at system shutdown time.

The fact that we should call drm_atomic_helper_shutdown() in the case
of OS shutdown/restart comes straight out of the kernel doc "driver
instance overview" in drm_drv.c.

Suggested-by: Maxime Ripard <mripard at kernel.org>
Reviewed-by: Maxime Ripard <mripard at kernel.org>
Signed-off-by: Douglas Anderson <dianders at chromium.org>
---
This commit is only compile-time tested. I made my best guess about
how to fit this into the existing code. If someone wishes a different
style, please yell.

(no changes since v1)

 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 ++++++
 5 files changed, 30 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c
b/drivers/gpu/drm/nouveau/nouveau_display.c
index d8c92521226d..05c3688ccb76 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -642,6 +642,15 @@ nouveau_display_fini(struct drm_device *dev, bool suspend,
bool runtime)
 	disp->fini(dev, runtime, suspend);
 }
 
+void
+nouveau_display_shutdown(struct drm_device *dev)
+{
+	if (drm_drv_uses_atomic_modeset(dev))
+		drm_atomic_helper_shutdown(dev);
+	else
+		drm_helper_force_disable_all(dev);
+}
+
 static void
 nouveau_display_create_properties(struct drm_device *dev)
 {
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.h
b/drivers/gpu/drm/nouveau/nouveau_display.h
index 2ab2ddb1eadf..9df62e833cda 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.h
+++ b/drivers/gpu/drm/nouveau/nouveau_display.h
@@ -47,6 +47,7 @@ void nouveau_display_destroy(struct drm_device *dev);
 int  nouveau_display_init(struct drm_device *dev, bool resume, bool runtime);
 void nouveau_display_hpd_resume(struct drm_device *dev);
 void nouveau_display_fini(struct drm_device *dev, bool suspend, bool runtime);
+void nouveau_display_shutdown(struct drm_device *dev);
 int  nouveau_display_suspend(struct drm_device *dev, bool runtime);
 void nouveau_display_resume(struct drm_device *dev, bool runtime);
 int  nouveau_display_vblank_enable(struct drm_crtc *crtc);
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 50589f982d1a..8ecfd66b7aab 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -879,6 +879,18 @@ nouveau_drm_remove(struct pci_dev *pdev)
 	pci_disable_device(pdev);
 }
 
+void
+nouveau_drm_device_shutdown(struct drm_device *dev)
+{
+	nouveau_display_shutdown(dev);
+}
+
+static void
+nouveau_drm_shutdown(struct pci_dev *pdev)
+{
+	nouveau_drm_device_shutdown(pci_get_drvdata(pdev));
+}
+
 static int
 nouveau_do_suspend(struct drm_device *dev, bool runtime)
 {
@@ -1346,6 +1358,7 @@ nouveau_drm_pci_driver = {
 	.id_table = nouveau_drm_pci_table,
 	.probe = nouveau_drm_probe,
 	.remove = nouveau_drm_remove,
+	.shutdown = nouveau_drm_shutdown,
 	.driver.pm = &nouveau_pm_ops,
 };
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h
b/drivers/gpu/drm/nouveau/nouveau_drv.h
index 3666a7403e47..aa936cabb6cf 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -327,6 +327,7 @@ struct drm_device *
 nouveau_platform_device_create(const struct nvkm_device_tegra_func *,
 			       struct platform_device *, struct nvkm_device **);
 void nouveau_drm_device_remove(struct drm_device *dev);
+void nouveau_drm_device_shutdown(struct drm_device *dev);
 
 #define NV_PRINTK(l,c,f,a...) do {                                            
\
 	struct nouveau_cli *_cli = (c);                                        \
diff --git a/drivers/gpu/drm/nouveau/nouveau_platform.c
b/drivers/gpu/drm/nouveau/nouveau_platform.c
index 23cd43a7fd19..b2e82a96411c 100644
--- a/drivers/gpu/drm/nouveau/nouveau_platform.c
+++ b/drivers/gpu/drm/nouveau/nouveau_platform.c
@@ -50,6 +50,11 @@ static int nouveau_platform_remove(struct platform_device
*pdev)
 	return 0;
 }
 
+static void nouveau_platform_shutdown(struct platform_device *pdev)
+{
+	nouveau_drm_device_shutdown(platform_get_drvdata(pdev));
+}
+
 #if IS_ENABLED(CONFIG_OF)
 static const struct nvkm_device_tegra_func gk20a_platform_data = {
 	.iommu_bit = 34,
@@ -94,4 +99,5 @@ struct platform_driver nouveau_platform_driver = {
 	},
 	.probe = nouveau_platform_probe,
 	.remove = nouveau_platform_remove,
+	.shutdown = nouveau_platform_shutdown,
 };
-- 
2.42.0.515.g380fc7ccd1-goog