drm/vc4: kms: Fix VBLANK reporting on a disabled CRTC

[platform/kernel/linux-rpi.git] / drivers / gpu / drm / vc4 / vc4_kms.c

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 06b291f..a552221 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -651,6 +651,14 @@ static const struct drm_private_state_funcs vc4_load_tracker_state_funcs = {
  *   need to consider all the running CRTCs in the DRM device to assign
  *   a FIFO, not just the one in the state.
  *
+ * - To fix the above, we can't use drm_atomic_get_crtc_state on all
+ *   enabled CRTCs to pull their CRTC state into the global state, since
+ *   a page flip would start considering their vblank to complete. Since
+ *   we don't have a guarantee that they are actually active, that
+ *   vblank might never happen, and shouldn't even be considered if we
+ *   want to do a page flip on a single CRTC. That can be tested by
+ *   doing a modetest -v first on HDMI1 and then on HDMI0.
+ *
  * - Since we need the pixelvalve to be disabled and enabled back when
  *   the FIFO is changed, we should keep the FIFO assigned for as long
  *   as the CRTC is enabled, only considering it free again once that
@@ -661,8 +669,8 @@ static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
                                      struct drm_atomic_state *state)
 {
        unsigned long unassigned_channels = GENMASK(NUM_CHANNELS - 1, 0);
-       struct vc4_dev *vc4 = to_vc4_dev(state->dev);
        struct drm_crtc_state *old_crtc_state, *new_crtc_state;
+       struct drm_crtc_state *crtc_state;
        struct drm_crtc *crtc;
        unsigned int i;
 
@@ -674,14 +682,13 @@ static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
         * the same CRTCs, instead of evaluating only the CRTC being
         * modified.
         */
-       list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
-               struct drm_crtc_state *crtc_state;
-               if (!crtc->state->enable)
+       for_each_new_or_current_crtc_state(state, crtc, crtc_state) {
+               struct vc4_crtc_state *vc4_crtc_state;
+               if (!crtc_state->enable)
                        continue;
 
-               crtc_state = drm_atomic_get_crtc_state(state, crtc);
-               if (IS_ERR(crtc_state))
-                       return PTR_ERR(crtc_state);
+               vc4_crtc_state = to_vc4_crtc_state(crtc_state);
+               unassigned_channels &= ~BIT(vc4_crtc_state->assigned_channel);
        }
 
        for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
@@ -697,10 +704,8 @@ static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
                if (!new_crtc_state->enable)
                        continue;
 
-               if (new_vc4_crtc_state->assigned_channel != VC4_HVS_CHANNEL_DISABLED) {
-                       unassigned_channels &= ~BIT(new_vc4_crtc_state->assigned_channel);
+               if (new_vc4_crtc_state->assigned_channel != VC4_HVS_CHANNEL_DISABLED)
                        continue;
-               }
 
                /*
                 * The problem we have to solve here is that we have