[Bug 212293] [amdgpu] divide error: 0000 on resume from S3

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=212293

--- Comment #6 from Sefa Eyeoglu (contact at scrumplex.net) ---
Okay I tried to debug it by printing.

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 573cf17262da..8e6b890ad611 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -9271,6 +9271,8 @@ static int dm_check_crtc_cursor(struct drm_atomic_state
*state,
                return 0;
        }

+       printk("SCRUMPLEX_DEBUG %d %d %d %d", new_cursor_state->src_w,
new_cursor_state->src_h, new_primary_state->src_w, new_primary_state->src_h);
+
        cursor_scale_w = new_cursor_state->crtc_w * 1000 /
                         (new_cursor_state->src_w >> 16);
        cursor_scale_h = new_cursor_state->crtc_h * 1000 /
-- 
2.31.0


This adds my very professional printk, which outputs all values that are used
to divide in any way later.


While reproducing the issue I got the following output

[   89.850437] SCRUMPLEX_DEBUG 8388608 8388608 0 0


So some weird state is causing the src_w and src_h values of
"new_primary_state" to be 0.

That would explain the issue to me. Now I don't know enough about
drm_plane_state and drm_atomic_get_new_plane_state to say why this is like
this. But as with most of these kinds of issues. A simple condition check
beforehand would solve this issue.

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