[PATCH 10/13] drm/amdgpu: Catch register access while GMUX keeps the GPU off

[Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>]

From: Andre Eikmeyer <dev@deq.rocks>

As mentioned previous any access to the GPU when the GMUX has
shut off the rails results in a CPU CATTER, skip and report
any register access after the GPU was runtime suspended for GMUX power-off.

Signed-off-by: Andre Eikmeyer <dev@deq.rocks>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h           |  2 ++
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c    |  5 ++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c       |  5 ++++
 .../gpu/drm/amd/amdgpu/amdgpu_reg_access.c    | 24 +++++++++++++++++++
 4 files changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 6fd607587..ac8dfc3ab 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -881,6 +881,8 @@ struct amdgpu_device {
 	/* enable runtime pm on the device */
 	bool                            in_runpm;
 	bool                            has_pr3;
+	/* GMUX has cut power, any register access would hang the PEG link */
+	bool                            gmux_off;
 
 	bool                            ucode_sysfs_en;
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index c1f196242..8185934b4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -946,6 +946,11 @@ bool amdgpu_device_skip_hw_access(struct amdgpu_device *adev)
 	if (adev->no_hw_access)
 		return true;
 
+	if (unlikely(READ_ONCE(adev->gmux_off))) {
+		WARN_RATELIMIT(1, "%s: register access while powered off by GMUX\n",
+					dev_name(adev->dev));
+		return true;
+	}
 #ifdef CONFIG_LOCKDEP
 	/*
 	 * This is a bit complicated to understand, so worth a comment. What we assert
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 5ad7b6dd8..135798c76 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -2932,6 +2932,9 @@ static int amdgpu_pmops_runtime_suspend(struct device *dev)
 		amdgpu_device_baco_enter(adev);
 	}
 
+	if (adev->pm.rpm_mode == AMDGPU_RUNPM_GMUX)
+		WRITE_ONCE(adev->gmux_off, true);
+
 	dev_dbg(&pdev->dev, "asic/device is runtime suspended\n");
 
 	return 0;
@@ -2960,6 +2963,8 @@ static int amdgpu_pmops_runtime_resume(struct device *dev)
 	if (adev->pm.rpm_mode == AMDGPU_RUNPM_NONE)
 		return -EINVAL;
 
+	WRITE_ONCE(adev->gmux_off, false);
+
 	/* Avoids registers access if device is physically gone */
 	if (!pci_device_is_present(adev->pdev))
 		adev->no_hw_access = true;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_reg_access.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_reg_access.c
index 7468855c1..bb5dbeb7f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_reg_access.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_reg_access.c
@@ -594,6 +594,9 @@ u32 amdgpu_device_indirect_rreg(struct amdgpu_device *adev, u32 reg_addr)
 	void __iomem *pcie_data_offset;
 	u32 r;
 
+	if (amdgpu_device_skip_hw_access(adev))
+		return 0;
+
 	pcie_index = adev->nbio.funcs->get_pcie_index_offset(adev);
 	pcie_data = adev->nbio.funcs->get_pcie_data_offset(adev);
 
@@ -677,6 +680,12 @@ u64 amdgpu_device_indirect_rreg64(struct amdgpu_device *adev, u32 reg_addr)
 	void __iomem *pcie_data_offset;
 	u64 r;
 
+	if (amdgpu_device_skip_hw_access(adev))
+		return 0;
+
+	if (amdgpu_device_skip_hw_access(adev))
+		return 0;
+
 	pcie_index = adev->nbio.funcs->get_pcie_index_offset(adev);
 	pcie_data = adev->nbio.funcs->get_pcie_data_offset(adev);
 
@@ -706,6 +715,9 @@ u64 amdgpu_device_indirect_rreg64_ext(struct amdgpu_device *adev, u64 reg_addr)
 	void __iomem *pcie_data_offset;
 	u64 r;
 
+	if (amdgpu_device_skip_hw_access(adev))
+		return 0;
+
 	pcie_index = adev->nbio.funcs->get_pcie_index_offset(adev);
 	pcie_data = adev->nbio.funcs->get_pcie_data_offset(adev);
 	if ((reg_addr >> 32) && (adev->nbio.funcs->get_pcie_index_hi_offset))
@@ -762,6 +774,9 @@ void amdgpu_device_indirect_wreg(struct amdgpu_device *adev, u32 reg_addr,
 	void __iomem *pcie_index_offset;
 	void __iomem *pcie_data_offset;
 
+	if (amdgpu_device_skip_hw_access(adev))
+		return;
+
 	pcie_index = adev->nbio.funcs->get_pcie_index_offset(adev);
 	pcie_data = adev->nbio.funcs->get_pcie_data_offset(adev);
 
@@ -784,6 +799,9 @@ void amdgpu_device_indirect_wreg_ext(struct amdgpu_device *adev, u64 reg_addr,
 	void __iomem *pcie_index_hi_offset;
 	void __iomem *pcie_data_offset;
 
+	if (amdgpu_device_skip_hw_access(adev))
+		return;
+
 	pcie_index = adev->nbio.funcs->get_pcie_index_offset(adev);
 	pcie_data = adev->nbio.funcs->get_pcie_data_offset(adev);
 	if ((reg_addr >> 32) && (adev->nbio.funcs->get_pcie_index_hi_offset))
@@ -832,6 +850,9 @@ void amdgpu_device_indirect_wreg64(struct amdgpu_device *adev, u32 reg_addr,
 	void __iomem *pcie_index_offset;
 	void __iomem *pcie_data_offset;
 
+	if (amdgpu_device_skip_hw_access(adev))
+		return;
+
 	pcie_index = adev->nbio.funcs->get_pcie_index_offset(adev);
 	pcie_data = adev->nbio.funcs->get_pcie_data_offset(adev);
 
@@ -861,6 +882,9 @@ void amdgpu_device_indirect_wreg64_ext(struct amdgpu_device *adev, u64 reg_addr,
 	void __iomem *pcie_index_hi_offset;
 	void __iomem *pcie_data_offset;
 
+	if (amdgpu_device_skip_hw_access(adev))
+		return;
+
 	pcie_index = adev->nbio.funcs->get_pcie_index_offset(adev);
 	pcie_data = adev->nbio.funcs->get_pcie_data_offset(adev);
 	if ((reg_addr >> 32) && (adev->nbio.funcs->get_pcie_index_hi_offset))
-- 
2.55.0