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

["André Almeida" <andrealmeid@igalia.com>]

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 <andrealmeid@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
>>
>