On 30/10/2025 10:14, Jocelyn Falempe wrote:
In the atomic update callback, ast should call
drm_gem_fb_begin_cpu_access() to make sure it can read the
framebuffer from the CPU, otherwise the data might not be there due
to cache, and synchronization.
Tested on a Lenovo SE100, while rendering on the ArrowLake GPU with
i915 driver, and using ast for display.
Pushed to drm-misc-next, thanks.
--
Jocelyn
Suggested-by: Thomas Zimmermann <[email protected]>
Signed-off-by: Jocelyn Falempe <[email protected]>
---
v2:
* If begin_cpu_access() failed, skip the damage copy, but update the
pitch register (Thomas Zimmermann)
drivers/gpu/drm/ast/ast_mode.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 9ce874dba69c..77d6c2dcfc40 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -556,9 +556,14 @@ static void ast_primary_plane_helper_atomic_update(struct
drm_plane *plane,
ast_set_vbios_color_reg(ast, fb->format, ast_crtc_state->vmode);
}
- drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
- drm_atomic_for_each_plane_damage(&iter, &damage) {
- ast_handle_damage(ast_plane, shadow_plane_state->data, fb,
&damage);
+ /* if the buffer comes from another device */
+ if (drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE) == 0) {
+ drm_atomic_helper_damage_iter_init(&iter, old_plane_state,
plane_state);
+ drm_atomic_for_each_plane_damage(&iter, &damage) {
+ ast_handle_damage(ast_plane, shadow_plane_state->data, fb,
&damage);
+ }
+
+ drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
}
/*
base-commit: 4f9ffd2c80a2fa09dcc8dfa0482cb7e0fb6fcf6c
