Re: [PATCH] drm/amdgpu: optimize the padding with hw optimization

["Christian König" <christian.koenig@amd.com>]

Am 30.07.24 um 14:43 schrieb Sunil Khatri:
> 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@amd.com>
> Cc: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
> Cc: Tvrtko Ursulin <tursulin@igalia.com>
> Cc: Marek Olšák <marek.olsak@amd.com>
> Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c | 24 +++++++++++++++++++++---
>   1 file changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> index 853084a2ce7f..edf5b5c4d185 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> @@ -9397,6 +9397,24 @@ static void gfx_v10_0_emit_mem_sync(struct amdgpu_ring *ring)
>   	amdgpu_ring_write(ring, gcr_cntl); /* GCR_CNTL */
>   }
>   
> +static void amdgpu_gfx10_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);
> +}
> +
>   static void gfx_v10_ip_print(void *handle, struct drm_printer *p)
>   {
>   	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
> @@ -9588,7 +9606,7 @@ static const struct amdgpu_ring_funcs gfx_v10_0_ring_funcs_gfx = {
>   	.emit_hdp_flush = gfx_v10_0_ring_emit_hdp_flush,
>   	.test_ring = gfx_v10_0_ring_test_ring,
>   	.test_ib = gfx_v10_0_ring_test_ib,
> -	.insert_nop = amdgpu_ring_insert_nop,
> +	.insert_nop = amdgpu_gfx10_ring_insert_nop,
>   	.pad_ib = amdgpu_ring_generic_pad_ib,
>   	.emit_switch_buffer = gfx_v10_0_ring_emit_sb,
>   	.emit_cntxcntl = gfx_v10_0_ring_emit_cntxcntl,
> @@ -9629,7 +9647,7 @@ static const struct amdgpu_ring_funcs gfx_v10_0_ring_funcs_compute = {
>   	.emit_hdp_flush = gfx_v10_0_ring_emit_hdp_flush,
>   	.test_ring = gfx_v10_0_ring_test_ring,
>   	.test_ib = gfx_v10_0_ring_test_ib,
> -	.insert_nop = amdgpu_ring_insert_nop,
> +	.insert_nop = amdgpu_gfx10_ring_insert_nop,
>   	.pad_ib = amdgpu_ring_generic_pad_ib,
>   	.emit_wreg = gfx_v10_0_ring_emit_wreg,
>   	.emit_reg_wait = gfx_v10_0_ring_emit_reg_wait,
> @@ -9659,7 +9677,7 @@ static const struct amdgpu_ring_funcs gfx_v10_0_ring_funcs_kiq = {
>   	.emit_fence = gfx_v10_0_ring_emit_fence_kiq,
>   	.test_ring = gfx_v10_0_ring_test_ring,
>   	.test_ib = gfx_v10_0_ring_test_ib,
> -	.insert_nop = amdgpu_ring_insert_nop,
> +	.insert_nop = amdgpu_gfx10_ring_insert_nop,
>   	.pad_ib = amdgpu_ring_generic_pad_ib,
>   	.emit_rreg = gfx_v10_0_ring_emit_rreg,
>   	.emit_wreg = gfx_v10_0_ring_emit_wreg,