drm/amd/display: guard write a 0 post_divider value to HW

[ Upstream commit 5d666496c24129edeb2bcb500498b87cc64e7f07 ]

[why]
post_divider_value should not be 0.

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Signed-off-by: Ahmed, Muhammad <Ahmed.Ahmed@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c b/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c
index 68cd3258f4a97a9175aafa7fe22f2cc2618f858e..a64d8f3ec93a39c397d1633009191e82ac66b7c1 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c
+++ b/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c
@@ -47,7 +47,8 @@ static void dccg35_trigger_dio_fifo_resync(struct dccg *dccg)
        uint32_t dispclk_rdivider_value = 0;
 
        REG_GET(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_RDIVIDER, &dispclk_rdivider_value);
-       REG_UPDATE(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_WDIVIDER, dispclk_rdivider_value);
+       if (dispclk_rdivider_value != 0)
+               REG_UPDATE(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_WDIVIDER, dispclk_rdivider_value);
 }
 
 static void dcn35_set_dppclk_enable(struct dccg *dccg,