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   1 From df276f0a5aa865c7926d9d148605d1a59d1d4fbb Mon Sep 17 00:00:00 2001
   2 From: Dave Stevenson <dave.stevenson@raspberrypi.org>
   3 Date: Thu, 25 Jul 2019 17:27:44 +0100
   4 Subject: [PATCH] drm/vc4: Resolve the vblank warnings on mode
   5  switching
   6
   7 The details over when and how a driver is to service the
   8 vblank events are sketchy, and the fkms driver was triggering
   9 a kernel warning every time the crtc was enabled or disabled.
  10
  11 Copy the event handling as used by the vc4-kms driver slightly
  12 more closely, and we avoid the warnings.
  13
  14 https://github.com/raspberrypi/linux/issues/3020
  15
  16 Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
  17 ---
  18  drivers/gpu/drm/vc4/vc4_firmware_kms.c | 48 ++++++++++++++++++--------
  19  1 file changed, 33 insertions(+), 15 deletions(-)
  20
  21 --- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
  22 +++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
  23 @@ -933,6 +933,7 @@ static void vc4_crtc_mode_set_nofb(struc
  24
  25  static void vc4_crtc_disable(struct drm_crtc *crtc, struct drm_crtc_state *old_state)
  26  {
  27 +       struct drm_device *dev = crtc->dev;
  28         struct drm_plane *plane;
  29
  30         DRM_DEBUG_KMS("[CRTC:%d] vblanks off.\n",
  31 @@ -948,6 +949,35 @@ static void vc4_crtc_disable(struct drm_
  32
  33         drm_atomic_crtc_for_each_plane(plane, crtc)
  34                 vc4_plane_atomic_disable(plane, plane->state);
  35 +
  36 +       /*
  37 +        * Make sure we issue a vblank event after disabling the CRTC if
  38 +        * someone was waiting it.
  39 +        */
  40 +       if (crtc->state->event) {
  41 +               unsigned long flags;
  42 +
  43 +               spin_lock_irqsave(&dev->event_lock, flags);
  44 +               drm_crtc_send_vblank_event(crtc, crtc->state->event);
  45 +               crtc->state->event = NULL;
  46 +               spin_unlock_irqrestore(&dev->event_lock, flags);
  47 +       }
  48 +}
  49 +
  50 +static void vc4_crtc_consume_event(struct drm_crtc *crtc)
  51 +{
  52 +       struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
  53 +       struct drm_device *dev = crtc->dev;
  54 +       unsigned long flags;
  55 +
  56 +       crtc->state->event->pipe = drm_crtc_index(crtc);
  57 +
  58 +       WARN_ON(drm_crtc_vblank_get(crtc) != 0);
  59 +
  60 +       spin_lock_irqsave(&dev->event_lock, flags);
  61 +       vc4_crtc->event = crtc->state->event;
  62 +       crtc->state->event = NULL;
  63 +       spin_unlock_irqrestore(&dev->event_lock, flags);
  64  }
  65
  66  static void vc4_crtc_enable(struct drm_crtc *crtc, struct drm_crtc_state *old_state)
  67 @@ -957,6 +987,7 @@ static void vc4_crtc_enable(struct drm_c
  68         DRM_DEBUG_KMS("[CRTC:%d] vblanks on.\n",
  69                       crtc->base.id);
  70         drm_crtc_vblank_on(crtc);
  71 +       vc4_crtc_consume_event(crtc);
  72
  73         /* Unblank the planes (if they're supposed to be displayed). */
  74         drm_atomic_crtc_for_each_plane(plane, crtc)
  75 @@ -1028,23 +1059,10 @@ static int vc4_crtc_atomic_check(struct
  76  static void vc4_crtc_atomic_flush(struct drm_crtc *crtc,
  77                                   struct drm_crtc_state *old_state)
  78  {
  79 -       struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
  80 -       struct drm_device *dev = crtc->dev;
  81 -
  82         DRM_DEBUG_KMS("[CRTC:%d] crtc_atomic_flush.\n",
  83                       crtc->base.id);
  84 -       if (crtc->state->event) {
  85 -               unsigned long flags;
  86 -
  87 -               crtc->state->event->pipe = drm_crtc_index(crtc);
  88 -
  89 -               WARN_ON(drm_crtc_vblank_get(crtc) != 0);
  90 -
  91 -               spin_lock_irqsave(&dev->event_lock, flags);
  92 -               vc4_crtc->event = crtc->state->event;
  93 -               crtc->state->event = NULL;
  94 -               spin_unlock_irqrestore(&dev->event_lock, flags);
  95 -       }
  96 +       if (crtc->state->active && old_state->active && crtc->state->event)
  97 +               vc4_crtc_consume_event(crtc);
  98  }
  99
 100  static void vc4_crtc_handle_page_flip(struct vc4_crtc *vc4_crtc)