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drm/i915: fix haswell linetime watermarks calculation

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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>
This commit is contained in:
Paulo Zanoni 2013-05-03 17:23:40 -03:00 committed by Daniel Vetter
parent 7366937312
commit eaa591ec52
1 changed files with 1 additions and 1 deletions
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2
drivers/gpu/drm/i915/intel_pm.c
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@ -2093,7 +2093,7 @@ haswell_update_linetime_wm(struct drm_device *dev, struct drm_crtc *crtc)
* 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