On Wed, Jul 31, 2024 at 9:13 AM Sunil Khatri <sunil.khatri@xxxxxxx> wrote:
>
> Adding NOP packets one by one in the ring
> does not use the CP efficiently.
>
> Solution:
> Use CP optimization while adding NOP packet's so PFP
> can discard NOP packets based on information of count
> from the Header instead of fetching all NOP packets
> one by one.
>
> Cc: Christian König <christian.koenig@xxxxxxx>
> Cc: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@xxxxxxx>
> Cc: Tvrtko Ursulin <tursulin@xxxxxxxxxx>
> Cc: Marek Olšák <marek.olsak@xxxxxxx>
> Signed-off-by: Sunil Khatri <sunil.khatri@xxxxxxx>
> ---
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c
> index f932c7ff85e3..29b3bf1b29b3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c
> @@ -5005,6 +5005,24 @@ static void gfx_v12_0_emit_mem_sync(struct amdgpu_ring *ring)
> amdgpu_ring_write(ring, gcr_cntl); /* GCR_CNTL */
> }
>
> +static void gfx_v12_ring_insert_nop(struct amdgpu_ring *ring, uint32_t num_nop)
> +{
> + int i;
> +
> + /* Header itself is a NOP packet */
> + if (num_nop == 1) {
> + amdgpu_ring_write(ring, ring->funcs->nop);
> + return;
> + }
> +
> + /* Max HW optimization till 0x3ffe, followed by remaining one NOP at a time*/
> + amdgpu_ring_write(ring, PACKET3(PACKET3_NOP, min(num_nop - 2, 0x3ffe)));
> +
> + /* Header is at index 0, followed by num_nops - 1 NOP packet's */
> + for (i = 1; i < num_nop; i++)
> + amdgpu_ring_write(ring, ring->funcs->nop);
This loop should be removed. I explained the reason in the gfx10 commit.
Marek
> +}
> +
> static void gfx_v12_ip_print(void *handle, struct drm_printer *p)
> {
> struct amdgpu_device *adev = (struct amdgpu_device *)handle;
> @@ -5186,7 +5204,7 @@ static const struct amdgpu_ring_funcs gfx_v12_0_ring_funcs_gfx = {
> .emit_hdp_flush = gfx_v12_0_ring_emit_hdp_flush,
> .test_ring = gfx_v12_0_ring_test_ring,
> .test_ib = gfx_v12_0_ring_test_ib,
> - .insert_nop = amdgpu_ring_insert_nop,
> + .insert_nop = gfx_v12_ring_insert_nop,
> .pad_ib = amdgpu_ring_generic_pad_ib,
> .emit_cntxcntl = gfx_v12_0_ring_emit_cntxcntl,
> .init_cond_exec = gfx_v12_0_ring_emit_init_cond_exec,
> @@ -5224,7 +5242,7 @@ static const struct amdgpu_ring_funcs gfx_v12_0_ring_funcs_compute = {
> .emit_hdp_flush = gfx_v12_0_ring_emit_hdp_flush,
> .test_ring = gfx_v12_0_ring_test_ring,
> .test_ib = gfx_v12_0_ring_test_ib,
> - .insert_nop = amdgpu_ring_insert_nop,
> + .insert_nop = gfx_v12_ring_insert_nop,
> .pad_ib = amdgpu_ring_generic_pad_ib,
> .emit_wreg = gfx_v12_0_ring_emit_wreg,
> .emit_reg_wait = gfx_v12_0_ring_emit_reg_wait,
> --
> 2.34.1
>
