[Intel-gfx] [PATCH] drm/i915: Increase atomic update vblank evasion time with lockdep

[Daniel Vetter]

All our mmio writes take forever with lockdep due to the constant
lock acquire&dropping we do. Ville has some patches to only acquire
the mmio spinlocks once instead for every single mmio, but those
aren't ready yet.

As an interim solution just extend our budget slightly when lockdep is
enabled, to avoid the rare and sporadic noise in CI.

v2: I forgot to add the FIXME comment ...

Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
Acked-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=103169
References: https://bugs.freedesktop.org/show_bug.cgi?id=103124
References: https://bugs.freedesktop.org/show_bug.cgi?id=102403
References: https://bugs.freedesktop.org/show_bug.cgi?id=103020
References: https://bugs.freedesktop.org/show_bug.cgi?id=103019
References: https://bugs.freedesktop.org/show_bug.cgi?id=102723
References: https://bugs.freedesktop.org/show_bug.cgi?id=102544
References: https://bugs.freedesktop.org/show_bug.cgi?id=103180
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 drivers/gpu/drm/i915/intel_sprite.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index b0d6e3e28d07..f29369622d2c 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -66,7 +66,13 @@ int intel_usecs_to_scanlines(const struct drm_display_mode *adjusted_mode,
 			    1000 * adjusted_mode->crtc_htotal);
 }
 
+/* FIXME: We should instead only take spinlocks once for the entire update
+ * instead of once per mmio. */
+#if IS_ENABLED(CONFIG_PROVE_LOCKING)
+#define VBLANK_EVASION_TIME_US 250
+#else
 #define VBLANK_EVASION_TIME_US 100
+#endif
 
 /**
  * intel_pipe_update_start() - start update of a set of display registers
-- 
2.14.1