Re: [PATCH v3 3/3] drm/amdgpu: Implement check_async_props for planes

[André Almeida]

Hi Sima,

Em 30/01/2024 07:56, Daniel Vetter escreveu:
On Sun, Jan 28, 2024 at 06:25:15PM -0300, André Almeida wrote:
AMD GPUs can do async flips with changes on more properties than just
the FB ID, so implement a custom check_async_props for AMD planes.
Allow amdgpu to do async flips with overlay planes as well.

Signed-off-by: André Almeida <andrealm...@igalia.com>
---
v3: allow overlay planes

This comment very much written with a lack of clearly better ideas, but:

Do we really need this much flexibility, especially for the first driver
adding the first few additional properties?

A simple bool on struct drm_plane to indicate whether async flips are ok
or not should also do this job here? Maybe a bit of work to roll that out
to the primary planes for current drivers, but not much. And wouldn't need
drivers to implement some very uapi-marshalling atomic code ...

Right, perhaps I can first write in the way you suggest, and later 
expand to the form I have proposed here if/when new properties arise.


Also we could probably remove the current drm_mode_config.async_flip flag
and entirely replace it with the per-plane one.
-Sima

  .../amd/display/amdgpu_dm/amdgpu_dm_plane.c   | 29 +++++++++++++++++++
  1 file changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
index 116121e647ca..ed75b69636b4 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
@@ -25,6 +25,7 @@
   */
  
  #include <drm/drm_atomic_helper.h>
+#include <drm/drm_atomic_uapi.h>
  #include <drm/drm_blend.h>
  #include <drm/drm_gem_atomic_helper.h>
  #include <drm/drm_plane_helper.h>
@@ -1430,6 +1431,33 @@ static void 
amdgpu_dm_plane_drm_plane_destroy_state(struct drm_plane *plane,
        drm_atomic_helper_plane_destroy_state(plane, state);
  }
  
+static int amdgpu_dm_plane_check_async_props(struct drm_property *prop,
+                                         struct drm_plane *plane,
+                                         struct drm_plane_state *plane_state,
+                                         struct drm_mode_object *obj,
+                                         u64 prop_value, u64 old_val)
+{
+       struct drm_mode_config *config = &plane->dev->mode_config;
+       int ret;
+
+       if (prop != config->prop_fb_id &&
+           prop != config->prop_in_fence_fd) {
+               ret = drm_atomic_plane_get_property(plane, plane_state,
+                                                   prop, &old_val);
+               return drm_atomic_check_prop_changes(ret, old_val, prop_value, 
prop);
+       }
+
+       if (plane_state->plane->type != DRM_PLANE_TYPE_PRIMARY &&
+           plane_state->plane->type != DRM_PLANE_TYPE_OVERLAY) {
+               drm_dbg_atomic(prop->dev,
+                              "[OBJECT:%d] Only primary or overlay planes can be 
changed during async flip\n",
+                              obj->id);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
  static const struct drm_plane_funcs dm_plane_funcs = {
        .update_plane   = drm_atomic_helper_update_plane,
        .disable_plane  = drm_atomic_helper_disable_plane,
@@ -1438,6 +1466,7 @@ static const struct drm_plane_funcs dm_plane_funcs = {
        .atomic_duplicate_state = amdgpu_dm_plane_drm_plane_duplicate_state,
        .atomic_destroy_state = amdgpu_dm_plane_drm_plane_destroy_state,
        .format_mod_supported = amdgpu_dm_plane_format_mod_supported,
+       .check_async_props = amdgpu_dm_plane_check_async_props,
  };
  
  int amdgpu_dm_plane_init(struct amdgpu_display_manager *dm,
--
2.43.0