Hi Changfeng,
that won't work, you can't add this to
amdgpu_ring_emit_reg_write_reg_wait_helper or break all read triggered
registers (like the semaphore ones).
Additional to that it will never work on GFX9, since the CP firmware
there uses the integrated write/wait command and you can't add an
additional dummy read there.
Regards,
Christian.
Am 25.10.19 um 16:22 schrieb Zhu, Changfeng:
> I try to write a patch based on the patch of Tuikov,Luben.
>
> Inspired by Luben,here is the patch:
>
> From 1980d8f1ed44fb9a84a5ea1f6e2edd2bc25c629a Mon Sep 17 00:00:00 2001
> From: changzhu <Changfeng.Zhu@xxxxxxx>
> Date: Thu, 10 Oct 2019 11:02:33 +0800
> Subject: [PATCH] drm/amdgpu: add dummy read by engines for some GCVM status
> registers
>
> The GRBM register interface is now capable of bursting 1 cycle per
> register wr->wr, wr->rd much faster than previous muticycle per
> transaction done interface. This has caused a problem where
> status registers requiring HW to update have a 1 cycle delay, due
> to the register update having to go through GRBM.
>
> SW may operate on an incorrect value if they write a register and
> immediately check the corresponding status register.
>
> Registers requiring HW to clear or set fields may be delayed by 1 cycle.
> For example,
>
> 1. write VM_INVALIDATE_ENG0_REQ mask = 5a
> 2. read VM_INVALIDATE_ENG0_ACKb till the ack is same as the request mask = 5a
> a. HW will reset VM_INVALIDATE_ENG0_ACK = 0 until invalidation is complete
> 3. write VM_INVALIDATE_ENG0_REQ mask = 5a
> 4. read VM_INVALIDATE_ENG0_ACK till the ack is same as the request mask = 5a
> a. First read of VM_INVALIDATE_ENG0_ACK = 5a instead of 0
> b. Second read of VM_INVALIDATE_ENG0_ACK = 0 because the remote GRBM h/w
> register takes one extra cycle to be cleared
> c. In this case,SW wil see a false ACK if they exit on first read
>
> Affected registers (only GC variant) | Recommended Dummy Read
> --------------------------------------+----------------------------
> VM_INVALIDATE_ENG*_ACK | VM_INVALIDATE_ENG*_REQ
> VM_L2_STATUS | VM_L2_STATUS
> VM_L2_PROTECTION_FAULT_STATUS | VM_L2_PROTECTION_FAULT_STATUS
> VM_L2_PROTECTION_FAULT_ADDR_HI/LO32 | VM_L2_PROTECTION_FAULT_ADDR_HI/LO32
> VM_L2_IH_LOG_BUSY | VM_L2_IH_LOG_BUSY
> MC_VM_L2_PERFCOUNTER_HI/LO | MC_VM_L2_PERFCOUNTER_HI/LO
> ATC_L2_PERFCOUNTER_HI/LO | ATC_L2_PERFCOUNTER_HI/LO
> ATC_L2_PERFCOUNTER2_HI/LO | ATC_L2_PERFCOUNTER2_HI/LO
>
> It also needs dummy read by engines for these gc registers.
>
> Change-Id: Ie028f37eb789966d4593984bd661b248ebeb1ac3
> Signed-off-by: changzhu <Changfeng.Zhu@xxxxxxx>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 5 +++++
> drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c | 2 ++
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 2 ++
> drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c | 4 ++++
> drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c | 18 ++++++++++++++++++
> 5 files changed, 31 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> index 4b3f58dbf36f..c2fbf6087ecf 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> @@ -392,6 +392,11 @@ void amdgpu_ring_emit_reg_write_reg_wait_helper(struct amdgpu_ring *ring,
> uint32_t ref, uint32_t mask)
> {
> amdgpu_ring_emit_wreg(ring, reg0, ref);
> +
> + /* wait for a cycle to reset vm_inv_eng0_ack */
> + if (ring->funcs->vmhub == AMDGPU_GFXHUB_0)
> + amdgpu_ring_emit_rreg(ring, reg0);
> +
> amdgpu_ring_emit_reg_wait(ring, reg1, mask, mask);
> }
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> index ef1975a5323a..104c47734316 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> @@ -5155,6 +5155,7 @@ static const struct amdgpu_ring_funcs gfx_v10_0_ring_funcs_gfx = {
> .patch_cond_exec = gfx_v10_0_ring_emit_patch_cond_exec,
> .preempt_ib = gfx_v10_0_ring_preempt_ib,
> .emit_tmz = gfx_v10_0_ring_emit_tmz,
> + .emit_rreg = gfx_v10_0_ring_emit_rreg,
> .emit_wreg = gfx_v10_0_ring_emit_wreg,
> .emit_reg_wait = gfx_v10_0_ring_emit_reg_wait,
> };
> @@ -5188,6 +5189,7 @@ static const struct amdgpu_ring_funcs gfx_v10_0_ring_funcs_compute = {
> .test_ib = gfx_v10_0_ring_test_ib,
> .insert_nop = amdgpu_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,
> .emit_reg_wait = gfx_v10_0_ring_emit_reg_wait,
> };
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 2f03bf533d41..d00b53de0fdc 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -6253,6 +6253,7 @@ static const struct amdgpu_ring_funcs gfx_v9_0_ring_funcs_gfx = {
> .init_cond_exec = gfx_v9_0_ring_emit_init_cond_exec,
> .patch_cond_exec = gfx_v9_0_ring_emit_patch_cond_exec,
> .emit_tmz = gfx_v9_0_ring_emit_tmz,
> + .emit_rreg = gfx_v9_0_ring_emit_rreg,
> .emit_wreg = gfx_v9_0_ring_emit_wreg,
> .emit_reg_wait = gfx_v9_0_ring_emit_reg_wait,
> .emit_reg_write_reg_wait = gfx_v9_0_ring_emit_reg_write_reg_wait,
> @@ -6289,6 +6290,7 @@ static const struct amdgpu_ring_funcs gfx_v9_0_ring_funcs_compute = {
> .insert_nop = amdgpu_ring_insert_nop,
> .pad_ib = amdgpu_ring_generic_pad_ib,
> .set_priority = gfx_v9_0_ring_set_priority_compute,
> + .emit_rreg = gfx_v9_0_ring_emit_rreg,
> .emit_wreg = gfx_v9_0_ring_emit_wreg,
> .emit_reg_wait = gfx_v9_0_ring_emit_reg_wait,
> .emit_reg_write_reg_wait = gfx_v9_0_ring_emit_reg_write_reg_wait,
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> index 3b00bce14cfb..dce6b651da1f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> @@ -346,6 +346,10 @@ 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);
>
> + /* wait for a cycle to reset vm_inv_eng0_ack */
> + if (ring->funcs->vmhub == AMDGPU_GFXHUB_0)
> + amdgpu_ring_emit_rreg(ring, hub->vm_inv_eng0_req + eng);
> +
> /* 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/sdma_v5_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
> index 3460c00f3eaa..baaa33467882 100644
> --- a/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
> @@ -38,6 +38,7 @@
> #include "navi10_sdma_pkt_open.h"
> #include "nbio_v2_3.h"
> #include "sdma_v5_0.h"
> +#include "nvd.h"
>
> MODULE_FIRMWARE("amdgpu/navi10_sdma.bin");
> MODULE_FIRMWARE("amdgpu/navi10_sdma1.bin");
> @@ -1147,6 +1148,22 @@ static void sdma_v5_0_ring_emit_vm_flush(struct amdgpu_ring *ring,
> amdgpu_gmc_emit_flush_gpu_tlb(ring, vmid, pd_addr);
> }
>
> +static void sdma_v5_0_ring_emit_rreg(struct amdgpu_ring *ring, uint32_t reg)
> +{
> + struct amdgpu_device *adev = ring->adev;
> +
> + amdgpu_ring_write(ring, PACKET3(PACKET3_COPY_DATA, 4));
> + amdgpu_ring_write(ring, 0 | /* src: register*/
> + (5 << 8) | /* dst: memory */
> + (1 << 20)); /* write confirm */
> + amdgpu_ring_write(ring, reg);
> + amdgpu_ring_write(ring, 0);
> + amdgpu_ring_write(ring, lower_32_bits(adev->wb.gpu_addr +
> + adev->virt.reg_val_offs * 4));
> + amdgpu_ring_write(ring, upper_32_bits(adev->wb.gpu_addr +
> + adev->virt.reg_val_offs * 4));
> +}
> +
> static void sdma_v5_0_ring_emit_wreg(struct amdgpu_ring *ring,
> uint32_t reg, uint32_t val)
> {
> @@ -1597,6 +1614,7 @@ static const struct amdgpu_ring_funcs sdma_v5_0_ring_funcs = {
> .test_ib = sdma_v5_0_ring_test_ib,
> .insert_nop = sdma_v5_0_ring_insert_nop,
> .pad_ib = sdma_v5_0_ring_pad_ib,
> + .emit_rreg = sdma_v5_0_ring_emit_rreg,
> .emit_wreg = sdma_v5_0_ring_emit_wreg,
> .emit_reg_wait = sdma_v5_0_ring_emit_reg_wait,
> .init_cond_exec = sdma_v5_0_ring_init_cond_exec,
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