From cc09164e9f4f8e3a48ccb6d820f953e38c43b372 Mon Sep 17 00:00:00 2001 From: Xiaojie Yuan Date: Fri, 16 Aug 2019 16:13:28 +0800 Subject: [PATCH 3608/4256] drm/amdgpu: add dummy read 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_ACK 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 will 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 Signed-off-by: Xiaojie Yuan Reviewed-by: Jack Xiao --- drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c | 15 +++++++++++++++ drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 16 ++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c index d83d8a6a1fc0..56f76a1f32ee 100644 --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c @@ -135,6 +135,14 @@ static int gmc_v10_0_process_interrupt(struct amdgpu_device *adev, addr |= ((u64)entry->src_data[1] & 0xf) << 44; if (!amdgpu_sriov_vf(adev)) { + /* + * Issue a dummy read to wait for the status register to + * be updated to avoid reading an incorrect value due to + * the new fast GRBM interface. + */ + if (entry->vmid_src == AMDGPU_GFXHUB_0) + RREG32(hub->vm_l2_pro_fault_status); + status = RREG32(hub->vm_l2_pro_fault_status); WREG32_P(hub->vm_l2_pro_fault_cntl, 1, ~1); } @@ -228,6 +236,13 @@ static void gmc_v10_0_flush_vm_hub(struct amdgpu_device *adev, uint32_t vmid, WREG32_NO_KIQ(hub->vm_inv_eng0_req + eng, tmp); + /* + * Issue a dummy read to wait for the ACK register to be cleared + * to avoid a false ACK due to the new fast GRBM interface. + */ + if (vmhub == AMDGPU_GFXHUB_0) + RREG32_NO_KIQ(hub->vm_inv_eng0_req + eng); + /* Wait for ACK with a delay.*/ for (i = 0; i < adev->usec_timeout; i++) { tmp = RREG32_NO_KIQ(hub->vm_inv_eng0_ack + eng); diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c index 57f0498152be..a22fbb8fe1a5 100644 --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c @@ -352,6 +352,14 @@ static int gmc_v9_0_process_interrupt(struct amdgpu_device *adev, /* If it's the first fault for this address, process it normally */ if (!amdgpu_sriov_vf(adev)) { + /* + * Issue a dummy read to wait for the status register to + * be updated to avoid reading an incorrect value due to + * the new fast GRBM interface. + */ + if (entry->vmid_src == AMDGPU_GFXHUB_0) + RREG32(hub->vm_l2_pro_fault_status); + status = RREG32(hub->vm_l2_pro_fault_status); WREG32_P(hub->vm_l2_pro_fault_cntl, 1, ~1); } @@ -480,6 +488,14 @@ static void gmc_v9_0_flush_gpu_tlb(struct amdgpu_device *adev, uint32_t vmid, spin_lock(&adev->gmc.invalidate_lock); WREG32_NO_KIQ(hub->vm_inv_eng0_req + eng, tmp); + + /* + * Issue a dummy read to wait for the ACK register to be cleared + * to avoid a false ACK due to the new fast GRBM interface. + */ + if (vmhub == AMDGPU_GFXHUB_0) + RREG32_NO_KIQ(hub->vm_inv_eng0_req + eng); + for (j = 0; j < adev->usec_timeout; j++) { tmp = RREG32_NO_KIQ(hub->vm_inv_eng0_ack + eng); if (tmp & (1 << vmid)) -- 2.17.1