On Fri, Jan 24, 2020 at 2:23 PM Harry Wentland harry.wentland@amd.com wrote:

From: Roman Li Roman.Li@amd.com

[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 colin.king@canonical.com Fixes: 5b5abe952607 drm/amd/display: make PSR static screen entry within 30 ms Cc: stable@vger.kernel.org Signed-off-by: Roman Li roman.li@amd.com Reviewed-by: Zhan Liu Zhan.Liu@amd.com

Acked-by: Alex Deucher alexander.deucher@amd.com

---

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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