[RFC 1/2] drm/amdgpu: Remove dynamic DRM scheduling priority override

[Christian König]

Adding Leo as well.

Am 06.09.24 um 20:06 schrieb Tvrtko Ursulin:
> From: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
>
> According to Christian the dynamic DRM priority override was only
> interesting before the hardware priority (dona via
> drm_sched_entity_modify_sched()) existed. Furthermore, both
> overrides also only work somewhat on paper while in reality they are only
> effective if the entity is idle, which is something userspace is unaware
> of when using the AMDGPU_SCHED_OP_*_PRIORITY_OVERRIDE uapi.
>
> Therefore follow Christian's advice and remove this call completely.

The only potential use case I can come up with would be for multimedia 
engines since we never implemented the hardware priority handling for them.

@Leo do we have any use case relying on that? As far as I know it 
doesn't work for UVD/VCE anyway because those engines can't switch loads 
and for VCN we should probably just implement different hw priorities.

Christian.

>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 4 ----
>   1 file changed, 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> index c43d1b6e5d66..2480b3227dad 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> @@ -820,10 +820,6 @@ static void amdgpu_ctx_set_entity_priority(struct amdgpu_ctx *ctx,
>   	struct drm_gpu_scheduler **scheds = NULL;
>   	unsigned num_scheds;
>   
> -	/* set sw priority */
> -	drm_sched_entity_set_priority(&aentity->entity,
> -				      amdgpu_ctx_to_drm_sched_prio(priority));
> -
>   	/* set hw priority */
>   	if (hw_ip == AMDGPU_HW_IP_COMPUTE || hw_ip == AMDGPU_HW_IP_GFX) {
>   		hw_prio = amdgpu_ctx_get_hw_prio(ctx, hw_ip);