On Thu, Oct 24, 2019 at 09:16:55PM +0000, Tuikov, Luben wrote:
> The GRBM interface is now capable of bursting 1-cycle op per register,
> a WRITE followed by another WRITE, or a WRITE followed by a READ--much
> faster than previous muti-cycle per completed-transaction interface.
> This causes a problem, whereby status registers requiring a read/write
> by hardware, have a 1-cycle delay, due to the register update having
> to go through GRBM interface.
>
> This patch adds this delay.
>
> A one cycle read op is added after updating the invalidate request and
> before reading the invalidate-ACK status.
>
> See also commit
> 534991731cb5fa94b5519957646cf849ca10d17d.
>
> Signed-off-by: Luben Tuikov <luben.tuikov@xxxxxxx>
> ---
> drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c | 4 ++--
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 4 ++--
> drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c | 9 +++++++++
> drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 8 ++++++++
> drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c | 2 +-
> 5 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> index ac43b1af69e3..0042868dbd53 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> @@ -5129,7 +5129,7 @@ static const struct amdgpu_ring_funcs gfx_v10_0_ring_funcs_gfx = {
> 5 + /* COND_EXEC */
> 7 + /* PIPELINE_SYNC */
> SOC15_FLUSH_GPU_TLB_NUM_WREG * 5 +
> - SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 7 +
> + SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 7 * 2 +
> 2 + /* VM_FLUSH */
> 8 + /* FENCE for VM_FLUSH */
> 20 + /* GDS switch */
> @@ -5182,7 +5182,7 @@ static const struct amdgpu_ring_funcs gfx_v10_0_ring_funcs_compute = {
> 5 + /* hdp invalidate */
> 7 + /* gfx_v10_0_ring_emit_pipeline_sync */
> SOC15_FLUSH_GPU_TLB_NUM_WREG * 5 +
> - SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 7 +
> + SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 7 * 2 +
> 2 + /* gfx_v10_0_ring_emit_vm_flush */
> 8 + 8 + 8, /* gfx_v10_0_ring_emit_fence x3 for user fence, vm fence */
> .emit_ib_size = 7, /* gfx_v10_0_ring_emit_ib_compute */
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 9fe95e7693d5..9a7a717208de 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -6218,7 +6218,7 @@ static const struct amdgpu_ring_funcs gfx_v9_0_ring_funcs_gfx = {
> 5 + /* COND_EXEC */
> 7 + /* PIPELINE_SYNC */
> SOC15_FLUSH_GPU_TLB_NUM_WREG * 5 +
> - SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 7 +
> + SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 7 * 2 +
> 2 + /* VM_FLUSH */
> 8 + /* FENCE for VM_FLUSH */
> 20 + /* GDS switch */
> @@ -6271,7 +6271,7 @@ static const struct amdgpu_ring_funcs gfx_v9_0_ring_funcs_compute = {
> 5 + /* hdp invalidate */
> 7 + /* gfx_v9_0_ring_emit_pipeline_sync */
> SOC15_FLUSH_GPU_TLB_NUM_WREG * 5 +
> - SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 7 +
> + SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 7 * 2 +
> 2 + /* gfx_v9_0_ring_emit_vm_flush */
> 8 + 8 + 8, /* gfx_v9_0_ring_emit_fence x3 for user fence, vm fence */
> .emit_ib_size = 7, /* gfx_v9_0_ring_emit_ib_compute */
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> index 6e1b25bd1fe7..100d526e9a42 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> @@ -346,6 +346,15 @@ static uint64_t
> gmc_v10_0_emit_flush_gpu_tlb(struct amdgpu_ring *ring,
>
> amdgpu_ring_emit_wreg(ring, hub->vm_inv_eng0_req + eng, req);
>
> + /* Insert a dummy read to delay one cycle before the ACK
> + * inquiry.
> + */
> + if (ring->funcs->type == AMDGPU_RING_TYPE_SDMA ||
> + ring->funcs->type == AMDGPU_RING_TYPE_GFX ||
> + ring->funcs->type == AMDGPU_RING_TYPE_COMPUTE)
> + amdgpu_ring_emit_reg_wait(ring,
> + hub->vm_inv_eng0_req + eng, 0, 0);
> +
> /* wait for the invalidate to complete */
> amdgpu_ring_emit_reg_wait(ring, hub->vm_inv_eng0_ack + eng,
> 1 << vmid, 1 << vmid);
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> index 9f2a893871ec..8f3097e45299 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> @@ -495,6 +495,14 @@ static uint64_t gmc_v9_0_emit_flush_gpu_tlb(struct amdgpu_ring *ring,
> amdgpu_ring_emit_wreg(ring, hub->ctx0_ptb_addr_hi32 + (2 * vmid),
> upper_32_bits(pd_addr));
>
> + /* Insert a dummy read to delay one cycle before the ACK
> + * inquiry.
> + */
> + if (ring->funcs->type == AMDGPU_RING_TYPE_GFX ||
> + ring->funcs->type == AMDGPU_RING_TYPE_COMPUTE)
> + amdgpu_ring_emit_reg_wait(ring,
> + hub->vm_inv_eng0_req + eng, 0, 0);
The workaround should be add a dummy read (one cycle delay) after we write VM_INVALIDATE_ENGx_REQ and before we poll the VM_INVALIDATE_ENGx_ACK.
If you add it here, that cannot resolve the issue. I think you should implement the dummy read in below function: amdgpu_ring_emit_reg_write_reg_wait().
Thanks,
Ray
> +
> amdgpu_ring_emit_reg_write_reg_wait(ring, hub->vm_inv_eng0_req + eng,
> hub->vm_inv_eng0_ack + eng,
> req, 1 << vmid);
> diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
> b/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
> index b8fdb192f6d6..0c41b4fdc58b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
> @@ -1588,7 +1588,7 @@ static const struct amdgpu_ring_funcs sdma_v5_0_ring_funcs = {
> 6 + /* sdma_v5_0_ring_emit_pipeline_sync */
> /* sdma_v5_0_ring_emit_vm_flush */
> SOC15_FLUSH_GPU_TLB_NUM_WREG * 3 +
> - SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 6 +
> + SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT * 6 * 2 +
> 10 + 10 + 10, /* sdma_v5_0_ring_emit_fence x3 for user fence, vm fence */
> .emit_ib_size = 7 + 6, /* sdma_v5_0_ring_emit_ib */
> .emit_ib = sdma_v5_0_ring_emit_ib,
> --
> 2.23.0.385.gbc12974a89
>
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