On Fri, Jan 24, 2020 at 2:23 PM Harry Wentland <harry.wentland@xxxxxxx> wrote:
>
> From: Roman Li <Roman.Li@xxxxxxx>
>
> [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@xxxxxxxxxxxxx>
> Fixes: 5b5abe952607 drm/amd/display: make PSR static screen entry within 30 ms
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Roman Li <roman.li@xxxxxxx>
> Reviewed-by: Zhan Liu <Zhan.Liu@xxxxxxx>
Acked-by: Alex Deucher <alexander.deucher@xxxxxxx>
> ---
> 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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