drm/i915/fbc: Use PLANE_HAS_FENCE to determine if the plane is fenced

Rather than trusting the cached value of plane_state->vma->fence to
imply whether the plane_state itself holds a reference on the
framebuffer's fence, use the information provided in the
plane_state->flags (PLANE_HAS_FENCE). Note that we still assume that FBC
is entirely bounded by the plane_state active life span; it's not clear
if that is a safe assumption.

Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180220134208.24988-4-chris@chris-wilson.co.uk

2 files changed, 11 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 3e1ad3f8e55d..1cdb543d4fce 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -667,6 +667,7 @@ struct intel_fbc {
          */
         struct intel_fbc_state_cache {
                 struct i915_vma *vma;
+                unsigned long flags;
 
                 struct {
                         unsigned int mode_flags;
@@ -705,6 +706,7 @@ struct intel_fbc {
          */
         struct intel_fbc_reg_params {
                 struct i915_vma *vma;
+                unsigned long flags;
 
                 struct {
                         enum pipe pipe;
diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 80682a418a70..2cc2eada5576 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -183,7 +183,7 @@ static void g4x_fbc_activate(struct drm_i915_private *dev_priv)
         else
                 dpfc_ctl |= DPFC_CTL_LIMIT_1X;
 
-        if (params->vma->fence) {
+        if (params->flags & PLANE_HAS_FENCE) {
                 dpfc_ctl |= DPFC_CTL_FENCE_EN | params->vma->fence->id;
                 I915_WRITE(DPFC_FENCE_YOFF, params->crtc.fence_y_offset);
         } else {
@@ -241,7 +241,7 @@ static void ilk_fbc_activate(struct drm_i915_private *dev_priv)
                 break;
         }
 
-        if (params->vma->fence) {
+        if (params->flags & PLANE_HAS_FENCE) {
                 dpfc_ctl |= DPFC_CTL_FENCE_EN;
                 if (IS_GEN5(dev_priv))
                         dpfc_ctl |= params->vma->fence->id;
@@ -324,7 +324,7 @@ static void gen7_fbc_activate(struct drm_i915_private *dev_priv)
                 break;
         }
 
-        if (params->vma->fence) {
+        if (params->flags & PLANE_HAS_FENCE) {
                 dpfc_ctl |= IVB_DPFC_CTL_FENCE_EN;
                 I915_WRITE(SNB_DPFC_CTL_SA,
                            SNB_CPU_FENCE_ENABLE |
@@ -753,6 +753,7 @@ static void intel_fbc_update_state_cache(struct intel_crtc *crtc,
         struct drm_framebuffer *fb = plane_state->base.fb;
 
         cache->vma = NULL;
+        cache->flags = 0;
 
         cache->crtc.mode_flags = crtc_state->base.adjusted_mode.flags;
         if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv))
@@ -778,6 +779,9 @@ static void intel_fbc_update_state_cache(struct intel_crtc *crtc,
         cache->fb.stride = fb->pitches[0];
 
         cache->vma = plane_state->vma;
+        cache->flags = plane_state->flags;
+        if (WARN_ON(cache->flags & PLANE_HAS_FENCE && !cache->vma->fence))
+                cache->flags &= ~PLANE_HAS_FENCE;
 }
 
 static bool intel_fbc_can_activate(struct intel_crtc *crtc)
@@ -817,7 +821,7 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc)
          * so have no fence associated with it) due to aperture constaints
          * at the time of pinning.
          */
-        if (!cache->vma->fence) {
+        if (!(cache->flags & PLANE_HAS_FENCE)) {
                 fbc->no_fbc_reason = "framebuffer not tiled or fenced";
                 return false;
         }
@@ -898,6 +902,7 @@ static void intel_fbc_get_reg_params(struct intel_crtc *crtc,
         memset(params, 0, sizeof(*params));
 
         params->vma = cache->vma;
+        params->flags = cache->flags;
 
         params->crtc.pipe = crtc->pipe;
         params->crtc.i9xx_plane = to_intel_plane(crtc->base.primary)->i9xx_plane;