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>

1 files changed, 3 insertions, 0 deletions

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);