[PATCH] drm/i915/dp_mst: Fix dsc mst bw overhead calculation

[Suraj Kandpal]

Fix the DSC flag assignment based on the dsc_slice_count returned
to avoid divide by zero error.

Fixes: 4e0837a8d00a ("drm/i915/dp_mst: Account for FEC and DSC overhead during BW allocation")
Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 4765bda154c1..bacd294d6bb6 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -105,11 +105,16 @@ static int intel_dp_mst_bw_overhead(const struct intel_crtc_state *crtc_state,
 	if (dsc) {
 		int num_joined_pipes = intel_crtc_num_joined_pipes(crtc_state);
 
-		flags |= DRM_DP_BW_OVERHEAD_DSC;
 		dsc_slice_count = intel_dp_dsc_get_slice_count(connector,
 							       adjusted_mode->clock,
 							       adjusted_mode->hdisplay,
 							       num_joined_pipes);
+		/*
+		 * Try with dsc only if dsc_slice_count has a sane value i.e value is no
+		 * 0
+		 */
+		if (dsc_slice_count)
+			flags |= DRM_DP_BW_OVERHEAD_DSC;
 	}
 
 	overhead = drm_dp_bw_overhead(crtc_state->lane_count,
-- 
2.43.2