drm/i915: wait for actual vblank, not just 20ms
Waiting for a hard coded 20ms isn't always enough to make sure a vblank
period has actually occurred, so add code to make sure we really have
passed through a vblank period (or that the pipe is off when disabling).
This prevents problems with mode setting and link training, and seems to
fix a bug like https://bugs.freedesktop.org/show_bug.cgi?id=29278, but
on an HP 8440p instead. Hopefully also fixes
https://bugs.freedesktop.org/show_bug.cgi?id=29141.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index a63e9a1..67e3ec1 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2081,6 +2081,7 @@
#define PIPE_DITHER_TYPE_ST01 (1 << 2)
/* Pipe A */
#define PIPEADSL 0x70000
+#define DSL_LINEMASK 0x00000fff
#define PIPEACONF 0x70008
#define PIPEACONF_ENABLE (1<<31)
#define PIPEACONF_DISABLE 0