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* [PATCH] drm/i915: Ensure plane->state->fb stays in sync with plane->fb
@ 2015-03-12 12:16 Xi Ruoyao
  2015-03-12 12:45 ` Jani Nikula
  0 siblings, 1 reply; 6+ messages in thread
From: Xi Ruoyao @ 2015-03-12 12:16 UTC (permalink / raw)
  To: jani.nikula, daniel.vetter; +Cc: Xi Ruoyao, Daniel Vetter, intel-gfx

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.
However, there are some places in kernel code 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 call it everywhere the driver tries to manually set
plane->fb outside of the atomic pipeline. In this function, use
drm_atomic_set_fb_for_plane instead of writing plane->state->fb
directly to keep the reference count right.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88909
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=93711
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Xi Ruoyao <xry111@outlook.com>
---
 This is modified from Matt Roper's patch to drm-intel-nightly with 
 commit id

 	afd65eb4cc0578a9c07d621acdb8a570e2782bf7

 However this bug exists in mainline kernel too, so I created this to
 fix it in mainline kernel.

 A minor change is to use drm_atomic_set_fb_for_plane instead of
 update reference count manually.

 drivers/gpu/drm/i915/intel_display.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e730789..c483f2f 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -37,6 +37,7 @@
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
 #include "i915_trace.h"
+#include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_crtc_helper.h>
@@ -2416,6 +2417,14 @@ 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)
+		drm_atomic_set_fb_for_plane(plane->state, plane->fb);
+}
+
 static void
 intel_find_plane_obj(struct intel_crtc *intel_crtc,
 		     struct intel_initial_plane_config *plane_config)
@@ -2462,6 +2471,8 @@ 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,
@@ -6650,6 +6661,7 @@ 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,
@@ -7687,6 +7699,7 @@ 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:
@@ -7778,6 +7791,7 @@ 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,
@@ -9816,6 +9830,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 	drm_gem_object_reference(&obj->base);
 
 	crtc->primary->fb = fb;
+	update_state_fb(crtc->primary);
 
 	work->pending_flip_obj = obj;
 
@@ -9884,6 +9899,7 @@ cleanup_unpin:
 cleanup_pending:
 	atomic_dec(&intel_crtc->unpin_work_count);
 	crtc->primary->fb = old_fb;
+	update_state_fb(crtc->primary);
 	drm_gem_object_unreference(&work->old_fb_obj->base);
 	drm_gem_object_unreference(&obj->base);
 	mutex_unlock(&dev->struct_mutex);
@@ -13718,6 +13734,7 @@ 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);
-- 
1.9.1

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^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH] drm/i915: Ensure plane->state->fb stays in sync with plane->fb
@ 2015-02-03 21:10 Matt Roper
  2015-02-04  9:39 ` Daniel Vetter
  0 siblings, 1 reply; 6+ messages in thread
From: Matt Roper @ 2015-02-03 21:10 UTC (permalink / raw)
  To: intel-gfx

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

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^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2015-03-13 12:36 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-03-12 12:16 [PATCH] drm/i915: Ensure plane->state->fb stays in sync with plane->fb Xi Ruoyao
2015-03-12 12:45 ` Jani Nikula
2015-03-12 16:12   ` Matt Roper
2015-03-13 12:38     ` Jani Nikula
  -- strict thread matches above, loose matches on Subject: below --
2015-02-03 21:10 Matt Roper
2015-02-04  9:39 ` Daniel Vetter

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