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>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 9dc9a85d000853b88d2be77e14fb2be84b829e83..b0aa6a4784c481a311bfab64fc00fd8a5fe13461 100644 (file)
--- 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);