From 534991731cb5fa94b5519957646cf849ca10d17d Mon Sep 17 00:00:00 2001
From: Xiaojie Yuan <xiaojie.yuan@amd.com>
Date: Fri, 16 Aug 2019 16:13:28 +0800
Subject: drm/amdgpu: add dummy read for some GCVM status registers
Git-commit: 534991731cb5fa94b5519957646cf849ca10d17d
Patch-mainline: v5.4-rc1
References: bsc#1152489
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 <xiaojie.yuan@amd.com>
Reviewed-by: Jack Xiao <Jack.Xiao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
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 8e8d712f5a6e..241a4e57cf4a 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
@@ -136,6 +136,14 @@ 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);
}
@@ -229,6 +237,13 @@ 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 7ae5f5860f31..8efda03920e3 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -356,6 +356,14 @@ 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);
}
@@ -484,6 +492,14 @@ 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))
--
2.28.0