From affb6683695429d411502933ee16feefa05ba067 Mon Sep 17 00:00:00 2001
From: George Shen <george.shen@amd.com>
Date: Fri, 20 May 2022 11:55:10 -0400
Subject: drm/amd/display: Fix divide-by-zero in DPPCLK and DISPCLK calculation
Git-commit: a3a885878e74d3d81e4742f8dd84faa27c8863ad
Patch-mainline: v6.0-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849
[Why]
Certain use cases will pass in zero in the new_clocks parameter for all
clocks. This results in a divide-by-zero error when attempting to round
up the new clock.
When new_clocks are zero, no rounding is required, so we can skip it.
[How]
Guard the division calculation with a check to make sure clocks are not
zero.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: George Shen <george.shen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
.../display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c
index bab85f3c9c67..8ece88ddfb5b 100644
--- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c
+++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn32/dcn32_clk_mgr.c
@@ -335,14 +335,16 @@ static void dcn32_update_dppclk_dispclk_freq(struct clk_mgr_internal *clk_mgr, s
int dpp_divider = 0;
int disp_divider = 0;
- dpp_divider = DENTIST_DIVIDER_RANGE_SCALE_FACTOR
- * clk_mgr->base.dentist_vco_freq_khz / new_clocks->dppclk_khz;
- disp_divider = DENTIST_DIVIDER_RANGE_SCALE_FACTOR
- * clk_mgr->base.dentist_vco_freq_khz / new_clocks->dispclk_khz;
-
- // Divide back the previous result to round up to the actual clock value that will be set from divider
- new_clocks->dppclk_khz = (DENTIST_DIVIDER_RANGE_SCALE_FACTOR * clk_mgr->base.dentist_vco_freq_khz) / dpp_divider;
- new_clocks->dispclk_khz = (DENTIST_DIVIDER_RANGE_SCALE_FACTOR * clk_mgr->base.dentist_vco_freq_khz) / disp_divider;
+ if (new_clocks->dppclk_khz) {
+ dpp_divider = DENTIST_DIVIDER_RANGE_SCALE_FACTOR
+ * clk_mgr->base.dentist_vco_freq_khz / new_clocks->dppclk_khz;
+ new_clocks->dppclk_khz = (DENTIST_DIVIDER_RANGE_SCALE_FACTOR * clk_mgr->base.dentist_vco_freq_khz) / dpp_divider;
+ }
+ if (new_clocks->dispclk_khz > 0) {
+ disp_divider = DENTIST_DIVIDER_RANGE_SCALE_FACTOR
+ * clk_mgr->base.dentist_vco_freq_khz / new_clocks->dispclk_khz;
+ new_clocks->dispclk_khz = (DENTIST_DIVIDER_RANGE_SCALE_FACTOR * clk_mgr->base.dentist_vco_freq_khz) / disp_divider;
+ }
}
static void dcn32_update_clocks(struct clk_mgr *clk_mgr_base,
--
2.38.1