From: Roman Li <[email protected]>

[Why]
Driver crash with psr feature enabled due to divide-by-zero error.
This is a regression after rework to calculate static screen frame
number entry time.

[How]
Correct order of operations to avoid divide-by-zero.

Cc: Colin Ian King <[email protected]>
Fixes: 5b5abe952607 drm/amd/display: make PSR static screen entry within 30 ms
Cc: [email protected]
Signed-off-by: Roman Li <[email protected]>
Reviewed-by: Zhan Liu <[email protected]>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index eed3ed7180fd..61c36c1520c2 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -8491,7 +8491,6 @@ bool amdgpu_dm_psr_enable(struct dc_stream_state *stream)
        /* Calculate number of static frames before generating interrupt to
         * enter PSR.
         */
-       unsigned int frame_time_microsec = 1000000 / vsync_rate_hz;
        // Init fail safe of 2 frames static
        unsigned int num_frames_static = 2;
 
@@ -8506,8 +8505,10 @@ bool amdgpu_dm_psr_enable(struct dc_stream_state *stream)
         * Calculate number of frames such that at least 30 ms of time has
         * passed.
         */
-       if (vsync_rate_hz != 0)
+       if (vsync_rate_hz != 0) {
+               unsigned int frame_time_microsec = 1000000 / vsync_rate_hz;
                num_frames_static = (30000 / frame_time_microsec) + 1;
+       }
 
        params.triggers.cursor_update = true;
        params.triggers.overlay_update = true;
-- 
2.25.0

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