drm/vblank: Unexport drm_vblank_cleanup

There's no reason for drivers to call this, and all the ones I've
removed looked very fishy:
- Proper quiescenting of the vblank machinery should be done by
  calling drm_crtc_vblank_off(), which is best done by shutting down
  the entire display engine with drm_atomic_helper_shutdown.

- Releasing of allocated memory is done by the core already, it calls
  drm_vblank_cleanup as a fallback.

- drm_vblank_cleanup also has checks for drivers which forget to clean
  up vblank interrupts.

This essentially reverts

commit e77cef9c2d87db835ad9d70cde4a9b00b0ca2262
Author: Jerome Glisse <jglisse@redhat.com>
Date:   Thu Jan 7 15:39:13 2010 +0100

    drm: Avoid calling vblank function is vblank wasn't initialized

which was done to fix a bug in radeon code with msi interrupts:

commit 003e69f9862bcda89a75c27750efdbc17ac02945
Author: Jerome Glisse <jglisse@redhat.com>
Date:   Thu Jan 7 15:39:14 2010 +0100

    drm/radeon/kms: Don't try to enable IRQ if we have no handler installed

Afaict from digging around in old code, this was needed to avoid
blowing up in the ums fallback, and has stopped serving it's purpose
long ago - if irq init fails, the driver fails to load, and there's
really no way to blow up anymore.

Long story short, this was most likely a small ums compat/fallback
hack that became a thing of it's own and got cargo-cult duplicated all
over the drm codebase for essentially no gain at all.

v2: Mention that for drivers with a ->release callback cleanup is
handled by drm_dev_fini() (Thierry).

Cc: Thierry Reding <treding@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170626161949.25629-2-daniel.vetter@ffwll.ch

1 files changed, 2 insertions, 17 deletions

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 7e3f59182571..05d043e9219f 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -394,19 +394,6 @@ static void vblank_disable_fn(unsigned long arg)
 	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 }
 
-/**
- * drm_vblank_cleanup - cleanup vblank support
- * @dev: DRM device
- *
- * This function cleans up any resources allocated in drm_vblank_init(). It is
- * called by the DRM core when @dev is finalized.
- *
- * Drivers can call drm_vblank_cleanup() if they need to quiescent the vblank
- * interrupt in their unload code. But in general this should be handled by
- * disabling all active &drm_crtc through e.g. drm_atomic_helper_shutdown, which
- * should end up calling drm_crtc_vblank_off().
- *
- */
 void drm_vblank_cleanup(struct drm_device *dev)
 {
 	unsigned int pipe;
@@ -428,7 +415,6 @@ void drm_vblank_cleanup(struct drm_device *dev)
 
 	dev->num_crtcs = 0;
 }
-EXPORT_SYMBOL(drm_vblank_cleanup);
 
 /**
  * drm_vblank_init - initialize vblank support
@@ -436,9 +422,8 @@ EXPORT_SYMBOL(drm_vblank_cleanup);
  * @num_crtcs: number of CRTCs supported by @dev
  *
  * This function initializes vblank support for @num_crtcs display pipelines.
- * Drivers do not need to call drm_vblank_cleanup(), cleanup is already handled
- * by the DRM core, or through calling drm_dev_fini() for drivers with a
- * &drm_driver.release callback.
+ * Cleanup is handled by the DRM core, or through calling drm_dev_fini() for
+ * drivers with a &drm_driver.release callback.
  *
  * Returns:
  * Zero on success or a negative error code on failure.