drm/i915: fix haswell linetime watermarks calculation
Move the "*8" calculation to the left side so we don't propagate
rounding errors. Also use DIV_ROUND_CLOSEST because that's what the
spec says we need to do.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 198d9c9..2c406dd 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2093,7 +2093,7 @@
* row at the given clock rate, multiplied by 8.
* */
temp |= PIPE_WM_LINETIME_TIME(
- ((mode->htotal * 1000) / mode->clock) * 8);
+ DIV_ROUND_CLOSEST(mode->htotal * 1000 * 8, mode->clock));
/* IPS watermarks are only used by pipe A, and are ignored by
* pipes B and C. They are calculated similarly to the common