[Intel-gfx] [PATCH] drm/i915: increase default latency constant

[Jesse Barnes]

Some i915/i945 platforms have a fairly high memory latency in certain
situations, so increase our constant a bit to avoid FIFO underruns.
The effect should be positive on other platforms as well; we'll have a
bit more insurance against a busy memory subsystem due to the extra
FIFO entries.

Fixes fdo bug #23368.

Tested-by: Sven Arvidsson <sa at whiz.se>
Tested-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d6fce21..80c9473 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2005,7 +2005,7 @@ static void igd_enable_cxsr(struct drm_device *dev, unsigned long clock,
 	return;
 }
 
-const static int latency_ns = 3000; /* default for non-igd platforms */
+const static int latency_ns = 5000; /* default for non-igd platforms */
 
 static int intel_get_fifo_size(struct drm_device *dev, int plane)
 {