On Tue, Nov 01, 2016 at 02:34:00PM +0100, Maarten Lankhorst wrote:
> Op 01-11-16 om 14:09 schreef Ville Syrjälä:
> > On Mon, Oct 17, 2016 at 02:37:00PM +0200, Maarten Lankhorst wrote:
> >> Add for_each_(old)(new)_(plane,connector,crtc)_in_state iterators to
> >> replace the old for_each_xxx_in_state ones. This is useful for >1 flip
> >> depth and getting rid of all xxx->state dereferences.
> >>
> >> Signed-off-by: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
> >> ---
> >> drivers/gpu/drm/drm_atomic.c | 6 +++
> >> drivers/gpu/drm/drm_atomic_helper.c | 52 +++++++++++++++++++++--
> >> drivers/gpu/drm/i915/intel_display.c | 11 ++---
> >> include/drm/drm_atomic.h | 81
> >> ++++++++++++++++++++++++++++++++++--
> >> include/drm/drm_atomic_helper.h | 3 ++
> >> 5 files changed, 142 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> >> index 5dd70540219c..120775fcfb70 100644
> >> --- a/drivers/gpu/drm/drm_atomic.c
> >> +++ b/drivers/gpu/drm/drm_atomic.c
> >> @@ -278,6 +278,8 @@ drm_atomic_get_crtc_state(struct drm_atomic_state
> >> *state,
> >> return ERR_PTR(-ENOMEM);
> >>
> >> state->crtcs[index].state = crtc_state;
> >> + state->crtcs[index].old_state = crtc->state;
> >> + state->crtcs[index].new_state = crtc_state;
> >> state->crtcs[index].ptr = crtc;
> >> crtc_state->state = state;
> >>
> >> @@ -640,6 +642,8 @@ drm_atomic_get_plane_state(struct drm_atomic_state
> >> *state,
> >>
> >> state->planes[index].state = plane_state;
> >> state->planes[index].ptr = plane;
> >> + state->planes[index].old_state = plane->state;
> >> + state->planes[index].new_state = plane_state;
> >> plane_state->state = state;
> >>
> >> DRM_DEBUG_ATOMIC("Added [PLANE:%d:%s] %p state to %p\n",
> >> @@ -931,6 +935,8 @@ drm_atomic_get_connector_state(struct drm_atomic_state
> >> *state,
> >>
> >> drm_connector_reference(connector);
> >> state->connectors[index].state = connector_state;
> >> + state->connectors[index].old_state = connector->state;
> >> + state->connectors[index].new_state = connector_state;
> >> state->connectors[index].ptr = connector;
> >> connector_state->state = state;
> >>
> >> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> >> b/drivers/gpu/drm/drm_atomic_helper.c
> >> index 07b432f43b98..fcb6e5b55217 100644
> >> --- a/drivers/gpu/drm/drm_atomic_helper.c
> >> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> >> @@ -2495,7 +2495,7 @@ EXPORT_SYMBOL(drm_atomic_helper_disable_all);
> >> *
> >> * See also:
> >> * drm_atomic_helper_duplicate_state(), drm_atomic_helper_disable_all(),
> >> - * drm_atomic_helper_resume()
> >> + * drm_atomic_helper_resume(), drm_atomic_helper_commit_duplicated_state()
> >> */
> >> struct drm_atomic_state *drm_atomic_helper_suspend(struct drm_device *dev)
> >> {
> >> @@ -2536,6 +2536,52 @@ unlock:
> >> EXPORT_SYMBOL(drm_atomic_helper_suspend);
> >>
> >> /**
> >> + * drm_atomic_helper_commit_duplicated_state - commit duplicated state
> >> + * @state: duplicated atomic state to commit
> >> + * @ctx: pointer to acquire_ctx to use for commit.
> >> + * @nonblock: commit the state non-blocking.
> >> + *
> >> + * The state returned by drm_atomic_helper_duplicate_state() and
> >> + * drm_atomic_helper_suspend() is partially invalid, and needs to
> >> + * be fixed up before commit.
> > So the old_state pointers are potentially invalid because whatever->state
> > may have changed since we duplicated the state?
>
> Yes when you use drm_atomic_helper_duplicate_state, and commit a different
> state before committing the duplicated state.
> This only happens during suspend/resume and gpu reset.
Kerneldoc should imo mention that suspend/resume is the only case this is
valid, and even then it depends upon the driver. Proper atomic commits
never keep drm_atomic_state around when dropping locks, so this can't
happen with an atomic ioctl. Please also directly cross-reference all
these functions.
-Daniel
>
> ~Maarten
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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