[RFC PATCH 1/4] drm/msm: register a fault handler for display mmu faults

[Abhinav Kumar]

In preparation to register a iommu fault handler for display
related modules, register a fault handler for the backing
mmu object of msm_kms.

Currently, the fault handler only captures the display snapshot
but we can expand this later if more information needs to be
added to debug display mmu faults.

Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
---
 drivers/gpu/drm/msm/msm_kms.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_kms.c b/drivers/gpu/drm/msm/msm_kms.c
index af6a6fcb1173..62c8e6163e81 100644
--- a/drivers/gpu/drm/msm/msm_kms.c
+++ b/drivers/gpu/drm/msm/msm_kms.c
@@ -200,6 +200,28 @@ struct msm_gem_address_space *msm_kms_init_aspace(struct drm_device *dev)
 	return aspace;
 }
 
+static int msm_kms_fault_handler(void *arg, unsigned long iova, int flags, void *data)
+{
+	struct msm_kms *kms = arg;
+	struct msm_disp_state *state;
+	int ret;
+
+	ret = mutex_lock_interruptible(&kms->dump_mutex);
+	if (ret)
+		return ret;
+
+	state = msm_disp_snapshot_state_sync(kms);
+
+	mutex_unlock(&kms->dump_mutex);
+
+	if (IS_ERR(state)) {
+		DRM_DEV_ERROR(kms->dev->dev, "failed to capture snapshot\n");
+		return PTR_ERR(state);
+	}
+
+	return 0;
+}
+
 void msm_drm_kms_uninit(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
@@ -261,6 +283,9 @@ int msm_drm_kms_init(struct device *dev, const struct drm_driver *drv)
 		goto err_msm_uninit;
 	}
 
+	if (kms->aspace)
+		msm_mmu_set_fault_handler(kms->aspace->mmu, kms, msm_kms_fault_handler);
+
 	drm_helper_move_panel_connectors_to_head(ddev);
 
 	drm_for_each_crtc(crtc, ddev) {
-- 
2.44.0