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. 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 -- 2.51.0
