linux-kernel - [PATCH 5.1 348/405] drm/amd/display: Fix Divide by 0 in memory calculations

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Date:   Wed, 29 May 2019 20:05:46 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Murton Liu <murton.liu@....com>,
        Aric Cyr <Aric.Cyr@....com>,
        Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>,
        Sivapiriyan Kumarasamy <Sivapiriyan.Kumarasamy@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.1 348/405] drm/amd/display: Fix Divide by 0 in memory calculations

[ Upstream commit 59979bf8be1784ebfc44215031c6c88ca22ae65d ]

Check if we get any values equal to 0, and set to 1 if so.

Signed-off-by: Murton Liu <murton.liu@....com>
Reviewed-by: Aric Cyr <Aric.Cyr@....com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>
Acked-by: Sivapiriyan Kumarasamy <Sivapiriyan.Kumarasamy@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../drm/amd/display/dc/dcn10/dcn10_dpp_dscl.c | 20 ++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_dpp_dscl.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_dpp_dscl.c
index c7642e7482970..ce21a290bf3e4 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_dpp_dscl.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_dpp_dscl.c
@@ -406,15 +406,25 @@ void dpp1_dscl_calc_lb_num_partitions(
 		int *num_part_y,
 		int *num_part_c)
 {
+	int lb_memory_size, lb_memory_size_c, lb_memory_size_a, num_partitions_a,
+	lb_bpc, memory_line_size_y, memory_line_size_c, memory_line_size_a;
+
 	int line_size = scl_data->viewport.width < scl_data->recout.width ?
 			scl_data->viewport.width : scl_data->recout.width;
 	int line_size_c = scl_data->viewport_c.width < scl_data->recout.width ?
 			scl_data->viewport_c.width : scl_data->recout.width;
-	int lb_bpc = dpp1_dscl_get_lb_depth_bpc(scl_data->lb_params.depth);
-	int memory_line_size_y = (line_size * lb_bpc + 71) / 72; /* +71 to ceil */
-	int memory_line_size_c = (line_size_c * lb_bpc + 71) / 72; /* +71 to ceil */
-	int memory_line_size_a = (line_size + 5) / 6; /* +5 to ceil */
-	int lb_memory_size, lb_memory_size_c, lb_memory_size_a, num_partitions_a;
+
+	if (line_size == 0)
+		line_size = 1;
+
+	if (line_size_c == 0)
+		line_size_c = 1;
+
+
+	lb_bpc = dpp1_dscl_get_lb_depth_bpc(scl_data->lb_params.depth);
+	memory_line_size_y = (line_size * lb_bpc + 71) / 72; /* +71 to ceil */
+	memory_line_size_c = (line_size_c * lb_bpc + 71) / 72; /* +71 to ceil */
+	memory_line_size_a = (line_size + 5) / 6; /* +5 to ceil */
 
 	if (lb_config == LB_MEMORY_CONFIG_1) {
 		lb_memory_size = 816;
-- 
2.20.1