From 3dd0be7a301bb0adcca4f7021cfd2e366ca90a0e Mon Sep 17 00:00:00 2001 From: Jocelyn Falempe Date: Thu, 30 Oct 2025 10:14:11 +0100 Subject: [PATCH] drm/ast: Handle framebuffer from dma-buf 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 Reviewed-by: Thomas Zimmermann Link: https://patch.msgid.link/20251030091627.340780-1-jfalempe@redhat.com Signed-off-by: Jocelyn Falempe --- 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 de7b6294ce40d..cd08990a10f93 100644 --- a/drivers/gpu/drm/ast/ast_mode.c +++ b/drivers/gpu/drm/ast/ast_mode.c @@ -557,9 +557,14 @@ 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); } /* -- 2.47.3