From 2c3a426a104c4ca50d2db4ed9a03022d6d2b744c Mon Sep 17 00:00:00 2001
From: David Galiffi <David.Galiffi@amd.com>
Date: Tue, 3 May 2022 18:30:25 -0400
Subject: drm/amd/display: Check if modulo is 0 before dividing.
Git-commit: 49947b906a6bd9668eaf4f9cf691973c25c26955
Patch-mainline: v5.19-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
[How & Why]
If a value of 0 is read, then this will cause a divide-by-0 panic.
Reviewed-by: Martin Leung <Martin.Leung@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: David Galiffi <David.Galiffi@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
index 5e6fea85a7b5..845aa8a1027d 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
@@ -1101,9 +1101,12 @@ static bool get_pixel_clk_frequency_100hz(
* not be programmed equal to DPREFCLK
*/
modulo_hz = REG_READ(MODULO[inst]);
- *pixel_clk_khz = div_u64((uint64_t)clock_hz*
- clock_source->ctx->dc->clk_mgr->dprefclk_khz*10,
- modulo_hz);
+ if (modulo_hz)
+ *pixel_clk_khz = div_u64((uint64_t)clock_hz*
+ clock_source->ctx->dc->clk_mgr->dprefclk_khz*10,
+ modulo_hz);
+ else
+ *pixel_clk_khz = 0;
} else {
/* NOTE: There is agreement with VBIOS here that MODULO is
* programmed equal to DPREFCLK, in which case PHASE will be
--
2.38.1