[PATCH AUTOSEL 5.18 45/68] drm/amd/display: Check if modulo is 0 before dividing.

From: Sasha Levin
Date: Tue Jun 07 2022 - 15:06:49 EST


From: David Galiffi <David.Galiffi@xxxxxxx>

[ Upstream commit 49947b906a6bd9668eaf4f9cf691973c25c26955 ]

[How & Why]
If a value of 0 is read, then this will cause a divide-by-0 panic.

Reviewed-by: Martin Leung <Martin.Leung@xxxxxxx>
Acked-by: Qingqing Zhuo <qingqing.zhuo@xxxxxxx>
Signed-off-by: David Galiffi <David.Galiffi@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 cc5128e67daf..8e9a7409c17a 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
@@ -1105,9 +1105,12 @@ 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
--
2.35.1