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| author | Noralf Trønnes <noralf@tronnes.org> | 2019-05-06 21:01:30 +0300 |
|---|---|---|
| committer | Noralf Trønnes <noralf@tronnes.org> | 2019-05-14 17:11:28 +0300 |
| commit | 03a9606e7feef902979bbc0601d6d93e764f251d (patch) | |
| tree | 14c3cdd6a72146a03461da62b60d17a539d4ffb6 /Documentation/gpu | |
| parent | 094aa54f0f9e9185babebf95745d71b07a84321c (diff) | |
| download | linux-03a9606e7feef902979bbc0601d6d93e764f251d.tar.xz | |
drm/fb-helper: Avoid race with DRM userspace
drm_fb_helper_is_bound() is used to check if DRM userspace is in control.
This is done by looking at the fb on the primary plane. By the time
fb-helper gets around to committing, it's possible that the facts have
changed.
Avoid this race by holding the drm_device->master_mutex lock while
committing. When DRM userspace does its first open, it will now wait
until fb-helper is done. The helper will stay away if there's a master.
Two igt tests fail with the new 'bail out if master' rule. Work around
this by relaxing this rule for drm_fb_helper_restore_fbdev_mode_unlocked()
until the tests have been fixed. Add todo entry for this.
Locking rule: Always take the fb-helper lock first.
v5: drm_fb_helper_restore_fbdev_mode_unlocked(): Use
restore_fbdev_mode_force()
v2:
- Remove drm_fb_helper_is_bound() (Daniel Vetter)
- No need to check fb_helper->dev->master in
drm_fb_helper_single_fb_probe(), restore_fbdev_mode() has the check.
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190506180139.6913-3-noralf@tronnes.org
Diffstat (limited to 'Documentation/gpu')
| -rw-r--r-- | Documentation/gpu/todo.rst | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 06ccff9165d5..66f05f4e469f 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -281,6 +281,14 @@ it to use drm_mode_hsync() instead. Contact: Sean Paul +drm_fb_helper tasks +------------------- + +- drm_fb_helper_restore_fbdev_mode_unlocked() should call restore_fbdev_mode() + not the _force variant so it can bail out if there is a master. But first + these igt tests need to be fixed: kms_fbcon_fbt@psr and + kms_fbcon_fbt@psr-suspend. + Core refactorings ================= |