From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Add some (probably overkill) locking to protect the vblank
timestamping constants updates during seamless M/N fastsets.
As everything should be naturally aligned I think the individual
pieces should probably end up updating atomically enough. So this
is only really meant to guarantee everyone sees a consistent whole.
All the drm_vblank.c usage is covered by vblank_time_lock,
and uncore.lock will take care of __intel_get_crtc_scanline()
that can also be called from outside the core vblank functionality.
Currently only crtc_clock and framedur_ns can change, but in
the future might fastset also across eg. vtotal/vblank_end
changes, so let's just grab the locks across the whole thing.
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_display.c | 24 +++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index a1fbdf32bd21..020320468967 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -5908,6 +5908,8 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state)
struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
struct drm_display_mode adjusted_mode;
+ int vmax_vblank_start = 0;
+ unsigned long irqflags;
drm_mode_init(&adjusted_mode, &crtc_state->hw.adjusted_mode);
@@ -5915,11 +5917,28 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state)
adjusted_mode.crtc_vtotal = crtc_state->vrr.vmax;
adjusted_mode.crtc_vblank_end = crtc_state->vrr.vmax;
adjusted_mode.crtc_vblank_start = intel_vrr_vmin_vblank_start(crtc_state);
- crtc->vmax_vblank_start = intel_vrr_vmax_vblank_start(crtc_state);
+ vmax_vblank_start = intel_vrr_vmax_vblank_start(crtc_state);
}
+ /*
+ * Belts and suspenders locking to guarantee everyone sees 100%
+ * consistent state during fastset seamless refresh rate changes.
+ *
+ * vblank_time_lock takes care of all drm_vblank.c stuff, and
+ * uncore.lock takes care of __intel_get_crtc_scanline() which
+ * may get called elsewhere as well.
+ *
+ * TODO maybe just protect everything (including
+ * __intel_get_crtc_scanline()) with vblank_time_lock?
+ * Need to audit everything to make sure it's safe.
+ */
+ spin_lock_irqsave(&dev_priv->drm.vblank_time_lock, irqflags);
+ spin_lock(&dev_priv->uncore.lock);
+
drm_calc_timestamping_constants(&crtc->base, &adjusted_mode);
+ crtc->vmax_vblank_start = vmax_vblank_start;
+
crtc->mode_flags = crtc_state->mode_flags;
/*
@@ -5963,6 +5982,9 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state)
} else {
crtc->scanline_offset = 1;
}
+
+ spin_unlock(&dev_priv->uncore.lock);
+ spin_unlock_irqrestore(&dev_priv->drm.vblank_time_lock, irqflags);
}
/*
--
2.39.2
