linux-kernel - Re: [PATCH v2 2/2] drm/amdgpu: Implement check_async

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Message-ID: <ca1faaec-461b-401c-a86a-e0929d282b51@amd.com>
Date: Mon, 22 Jan 2024 10:50:48 -0500
From: Harry Wentland <harry.wentland@....com>
To: Ville Syrjälä <ville.syrjala@...ux.intel.com>,
 André Almeida <andrealmeid@...lia.com>
Cc: daniel@...ll.ch, 'Marek Olšák' <maraeo@...il.com>,
 Michel Dänzer <michel.daenzer@...lbox.org>,
 linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
 Xaver Hugl <xaver.hugl@...il.com>, Pekka Paalanen <ppaalanen@...il.com>,
 dri-devel@...ts.freedesktop.org, kernel-dev@...lia.com,
 alexander.deucher@....com, Dave Airlie <airlied@...il.com>,
 christian.koenig@....com, Joshua Ashton <joshua@...ggi.es>
Subject: Re: [PATCH v2 2/2] drm/amdgpu: Implement check_async_props for planes



On 2024-01-19 13:25, Ville Syrjälä wrote:
> On Fri, Jan 19, 2024 at 03:12:35PM -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 IN_FENCE_ID and FB_DAMAGE_CLIPS
>> properties. For userspace to check if a driver support this two
>> properties, the strategy for now is to use TEST_ONLY commits.
>>
>> Signed-off-by: André Almeida <andrealmeid@...lia.com>
>> ---
>> v2: Drop overlay plane option for now
>>
>>   .../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..7afe8c1b62d4 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 &&
> 
> IN_FENCE should just be allowed always.
> 
>> +	    prop != config->prop_fb_damage_clips) {
> 
> This seems a bit dubious to me. How is amdgpu using the damage
> information during async flips?

Yeah, I'm also not sure this is right. Has anyone tested this
with a PSR SU panel?

Harry

> 
>> +		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) {
>> +		drm_dbg_atomic(prop->dev,
>> +			       "[OBJECT:%d] Only primary 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
>