From 24be4e4650de2fc323ee0737f945ad366b6c11cc Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Tue, 17 Mar 2015 11:40:04 +0200
Subject: [PATCH] drm/i915: check for div-by-zero in vlv_PLL_is_optimal

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/intel_display.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 9dc9a85d0008..b0aa6a4784c4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -786,6 +786,9 @@ static bool vlv_PLL_is_optimal(struct drm_device *dev, int target_freq,
 			       unsigned int best_error_ppm,
 			       unsigned int *error_ppm)
 {
+	if (WARN_ON_ONCE(!target_freq))
+		return false;
+
 	*error_ppm = div_u64(1000000ULL *
 				abs(target_freq - calculated_clock->dot),
 			     target_freq);
-- 
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