Am 09.12.21 um 09:49 schrieb Lang Yu:
It is useful to maintain error context when debugging
SW/FW issues. We introduce amdgpu_device_halt() for this
purpose. It will bring hardware to a kind of halt state,
so that no one can touch it any more.
Compare to a simple hang, the system will keep stable
at least for SSH access. Then it should be trivial to
inspect the hardware state and see what's going on.
Suggested-by: Christian Koenig <christian.koenig@xxxxxxx>
Suggested-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
Signed-off-by: Lang Yu <lang.yu@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 ++
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 39 ++++++++++++++++++++++
2 files changed, 41 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index c5cfe2926ca1..3f5f8f62aa5c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1317,6 +1317,8 @@ void amdgpu_device_flush_hdp(struct amdgpu_device *adev,
void amdgpu_device_invalidate_hdp(struct amdgpu_device *adev,
struct amdgpu_ring *ring);
+void amdgpu_device_halt(struct amdgpu_device *adev);
+
/* atpx handler */
#if defined(CONFIG_VGA_SWITCHEROO)
void amdgpu_register_atpx_handler(void);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index a1c14466f23d..62216627cc83 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -5634,3 +5634,42 @@ void amdgpu_device_invalidate_hdp(struct amdgpu_device *adev,
amdgpu_asic_invalidate_hdp(adev, ring);
}
+
+/**
+ * amdgpu_device_halt() - bring hardware to some kind of halt state
+ *
+ * @adev: amdgpu_device pointer
+ *
+ * Bring hardware to some kind of halt state so that no one can touch it
+ * any more. It will help to maintain error context when error occurred.
+ * Compare to a simple hang, the system will keep stable at least for SSH
+ * access. Then it should be trivial to inspect the hardware state and
+ * see what's going on. Implemented as following:
+ *
+ * 1. drm_dev_unplug() makes device inaccessible to user space(IOCTLs, etc),
+ * clears all CPU mappings to device, disallows remappings through page faults
+ * 2. amdgpu_irq_disable_all() disables all interrupts
+ * 3. amdgpu_fence_driver_hw_fini() signals all HW fences
+ * 4. amdgpu_device_unmap_mmio() clears all MMIO mappings
+ * 5. pci_disable_device() and pci_wait_for_pending_transaction()
+ * flush any in flight DMA operations
+ * 6. set adev->no_hw_access to true
+ */
+void amdgpu_device_halt(struct amdgpu_device *adev)
+{
+ struct pci_dev *pdev = adev->pdev;
+ struct drm_device *ddev = &adev->ddev;
+
+ drm_dev_unplug(ddev);
+
+ amdgpu_irq_disable_all(adev);
+
+ amdgpu_fence_driver_hw_fini(adev);
+
+ amdgpu_device_unmap_mmio(adev);
+
+ pci_disable_device(pdev);
+ pci_wait_for_pending_transaction(pdev);
+
+ adev->no_hw_access = true;
I think we need to reorder this, e.g. set adev->no_hw_access much
earlier for example. Andrey what do you think?
Apart from that sounds like the right idea to me.
Regards,
Christian.
+}
