[PATCH] drm/i915: Ensure plane->state->fb stays in sync with plane->fb

Matt Roper
2015-02-03T21:10:16Z

plane->state->fb and plane->fb should always reference the same FB so
that atomic and legacy codepaths have the same view of display state.
In commit

commit db068420560511de80ac59222644f2bdf278c3d5
Author: Matt Roper <matthew.d.roper@intel.com>
Date: Fri Jan 30 16:22:36 2015 -0800

drm/i915: Keep plane->state updated on pageflip

we already fixed one case where these two pointers could get out of
sync. However it turns out there are a few other places (mainly dealing
with initial FB setup at boot) that directly set plane->fb and neglect
to update plane->state->fb. If we never do a successful update through
the atomic pipeline, the RmFB cleanup code will look at the
plane->state->fb pointer, which has never actually been set to a
legitimate value, and try to clean it up, leading to BUG's.

Add a quick helper function to synchronize plane->state->fb with
plane->fb (and update reference counts accordingly) and call it
everywhere the driver tries to manually set plane->fb outside of the
atomic pipeline.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88909
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 213b870..e5c0579 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2410,6 +2410,20 @@ out_unref_obj:
return false;
}

+/* Update plane->state->fb to match plane->fb after driver-internal updates */
+static void
+update_state_fb(struct drm_plane *plane)
+{
+ if (plane->fb == plane->state->fb)
+ return;
+
+ if (plane->state->fb)
+ drm_framebuffer_unreference(plane->state->fb);
+ plane->state->fb = plane->fb;
+ if (plane->state->fb)
+ drm_framebuffer_reference(plane->state->fb);
+}
+
static void
intel_find_plane_obj(struct intel_crtc *intel_crtc,
struct intel_initial_plane_config *plane_config)
@@ -2456,6 +2470,8 @@ intel_find_plane_obj(struct intel_crtc *intel_crtc,
break;
}
}
+
+ update_state_fb(intel_crtc->base.primary);
}

static void i9xx_update_primary_plane(struct drm_crtc *crtc,
@@ -6635,6 +6651,7 @@ i9xx_get_initial_plane_config(struct intel_crtc *crtc,
plane_config->size);

crtc->base.primary->fb = fb;
+ update_state_fb(crtc->base.primary);
}

static void chv_crtc_clock_get(struct intel_crtc *crtc,
@@ -7672,6 +7689,7 @@ skylake_get_initial_plane_config(struct intel_crtc *crtc,
plane_config->size);

crtc->base.primary->fb = fb;
+ update_state_fb(crtc->base.primary);
return;

error:
@@ -7763,6 +7781,7 @@ ironlake_get_initial_plane_config(struct intel_crtc *crtc,
plane_config->size);

crtc->base.primary->fb = fb;
+ update_state_fb(crtc->base.primary);
}

static bool ironlake_get_pipe_config(struct intel_crtc *crtc,
@@ -9800,13 +9819,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
drm_gem_object_reference(&obj->base);

crtc->primary->fb = fb;
-
- /* Keep state structure in sync */
- if (crtc->primary->state->fb)
- drm_framebuffer_unreference(crtc->primary->state->fb);
- crtc->primary->state->fb = fb;
- if (crtc->primary->state->fb)
- drm_framebuffer_reference(crtc->primary->state->fb);
+ update_state_fb(crtc->primary);

work->pending_flip_obj = obj;

@@ -9875,6 +9888,7 @@ cleanup_unpin:
cleanup_pending:
atomic_dec(&intel_crtc->unpin_work_count);
crtc->primary->fb = old_fb;
+ update_state_fb(crtc->primary);
drm_framebuffer_unreference(work->old_fb);
drm_gem_object_unreference(&obj->base);
mutex_unlock(&dev->struct_mutex);
@@ -13709,6 +13723,7 @@ void intel_modeset_gem_init(struct drm_device *dev)
to_intel_crtc(c)->pipe);
drm_framebuffer_unreference(c->primary->fb);
c->primary->fb = NULL;
+ update_state_fb(c->primary);
}
}
mutex_unlock(&dev->struct_mutex);
--
1.8.5.1