[PATCH] drm/amdgpu: Enable tunneling on high-priority compute queues

[Alex Deucher]

On Fri, Dec 1, 2023 at 7:18 PM Friedrich Vock <friedrich.vock at gmx.de> wrote:
>
> This improves latency if the GPU is already busy with other work.
> This is useful for VR compositors that submit highly latency-sensitive
> compositing work on high-priority compute queues while the GPU is busy
> rendering the next frame.
>
> Userspace merge request:
> https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26462
>
> Signed-off-by: Friedrich Vock <friedrich.vock at gmx.de>

Applied with a minor change to bump the driver version as well so
userspace can detect this if necessary.  It shouldn't matter, but
better safe than sorry.

Alex

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu.h      |  1 +
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 10 ++++++----
>  drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c   |  3 ++-
>  drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c   |  3 ++-
>  4 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 9505dc8f9d69..4b923a156c4e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -790,6 +790,7 @@ struct amdgpu_mqd_prop {
>         uint64_t eop_gpu_addr;
>         uint32_t hqd_pipe_priority;
>         uint32_t hqd_queue_priority;
> +       bool allow_tunneling;
>         bool hqd_active;
>  };
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> index 231d49132a56..4d98e8879be8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> @@ -620,6 +620,10 @@ static void amdgpu_ring_to_mqd_prop(struct amdgpu_ring *ring,
>                                     struct amdgpu_mqd_prop *prop)
>  {
>         struct amdgpu_device *adev = ring->adev;
> +       bool is_high_prio_compute = ring->funcs->type == AMDGPU_RING_TYPE_COMPUTE &&
> +                                   amdgpu_gfx_is_high_priority_compute_queue(adev, ring);
> +       bool is_high_prio_gfx = ring->funcs->type == AMDGPU_RING_TYPE_GFX &&
> +                               amdgpu_gfx_is_high_priority_graphics_queue(adev, ring);
>
>         memset(prop, 0, sizeof(*prop));
>
> @@ -637,10 +641,8 @@ static void amdgpu_ring_to_mqd_prop(struct amdgpu_ring *ring,
>          */
>         prop->hqd_active = ring->funcs->type == AMDGPU_RING_TYPE_KIQ;
>
> -       if ((ring->funcs->type == AMDGPU_RING_TYPE_COMPUTE &&
> -            amdgpu_gfx_is_high_priority_compute_queue(adev, ring)) ||
> -           (ring->funcs->type == AMDGPU_RING_TYPE_GFX &&
> -            amdgpu_gfx_is_high_priority_graphics_queue(adev, ring))) {
> +       prop->allow_tunneling = is_high_prio_compute;
> +       if (is_high_prio_compute || is_high_prio_gfx) {
>                 prop->hqd_pipe_priority = AMDGPU_GFX_PIPE_PRIO_HIGH;
>                 prop->hqd_queue_priority = AMDGPU_GFX_QUEUE_PRIORITY_MAXIMUM;
>         }
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> index c8a3bf01743f..73f6d7e72c73 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> @@ -6593,7 +6593,8 @@ static int gfx_v10_0_compute_mqd_init(struct amdgpu_device *adev, void *m,
>         tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, ENDIAN_SWAP, 1);
>  #endif
>         tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, UNORD_DISPATCH, 0);
> -       tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, TUNNEL_DISPATCH, 0);
> +       tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, TUNNEL_DISPATCH,
> +                           prop->allow_tunneling);
>         tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, PRIV_STATE, 1);
>         tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, KMD_QUEUE, 1);
>         mqd->cp_hqd_pq_control = tmp;
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> index c659ef0f47ce..bdcf96df69e6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> @@ -3847,7 +3847,8 @@ static int gfx_v11_0_compute_mqd_init(struct amdgpu_device *adev, void *m,
>         tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, RPTR_BLOCK_SIZE,
>                             (order_base_2(AMDGPU_GPU_PAGE_SIZE / 4) - 1));
>         tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, UNORD_DISPATCH, 0);
> -       tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, TUNNEL_DISPATCH, 0);
> +       tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, TUNNEL_DISPATCH,
> +                           prop->allow_tunneling);
>         tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, PRIV_STATE, 1);
>         tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_CONTROL, KMD_QUEUE, 1);
>         mqd->cp_hqd_pq_control = tmp;
> --
> 2.43.0
>