drm/panthor: flush FW AS caches in slow reset path

In the off-chance that waiting for the firmware to signal its booted status
timed out in the fast reset path, one must flush the cache lines for the
entire FW VM address space before reloading the regions, otherwise stale
values eventually lead to a scheduler job timeout.

Signed-off-by: Adrián Larumbe <[email protected]>

drivers/gpu/drm/panthor/panthor_fw.c

@@ -1089,6 +1089,12 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
 		panthor_fw_stop(ptdev);
 		ptdev->fw->fast_reset = false;
 		drm_err(&ptdev->base, "FW fast reset failed, trying a slow reset");
+
+		ret = panthor_vm_flush_all(ptdev->fw->vm);
+		if (ret) {
+			drm_err(&ptdev->base, "FW slow reset failed (couldn't flush FW's AS l2cache)");
+			return ret;
+		}
 	}
 
 	/* Reload all sections, including RO ones. We're not supposed
@@ -1099,7 +1105,7 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
 
 	ret = panthor_fw_start(ptdev);
 	if (ret) {
-		drm_err(&ptdev->base, "FW slow reset failed");
+		drm_err(&ptdev->base, "FW slow reset failed (couldn't start the FW )");
 		return ret;
 	}
 

drivers/gpu/drm/panthor/panthor_mmu.c

@@ -873,14 +873,27 @@ static int panthor_vm_flush_range(struct panthor_vm *vm, u64 iova, u64 size)
 	if (!drm_dev_enter(&ptdev->base, &cookie))
 		return 0;
 
-	/* Flush the PTs only if we're already awake */
-	if (pm_runtime_active(ptdev->base.dev))
-		ret = mmu_hw_do_operation(vm, iova, size, AS_COMMAND_FLUSH_PT);
+	/*
+	 * If we made it this far, that means the device is awake, because
+	 * upon device suspension, all active VMs are given an AS id of -1
+	 */
+	ret = mmu_hw_do_operation(vm, iova, size, AS_COMMAND_FLUSH_PT);
 
 	drm_dev_exit(cookie);
 	return ret;
 }
 
+/**
+ * panthor_vm_flush_all() - Flush L2 caches for the entirety of a VM's AS
+ * @vm: VM whose cache to flush
+ *
+ * Return: 0 on success, a negative error code if flush failed.
+ */
+int panthor_vm_flush_all(struct panthor_vm *vm)
+{
+	return panthor_vm_flush_range(vm, vm->base.mm_start, vm->base.mm_range);
+}
+
 static int panthor_vm_unmap_pages(struct panthor_vm *vm, u64 iova, u64 size)
 {
 	struct panthor_device *ptdev = vm->ptdev;

drivers/gpu/drm/panthor/panthor_mmu.h

@@ -31,6 +31,7 @@ panthor_vm_get_bo_for_va(struct panthor_vm *vm, u64 va, u64 *bo_offset);
 int panthor_vm_active(struct panthor_vm *vm);
 void panthor_vm_idle(struct panthor_vm *vm);
 int panthor_vm_as(struct panthor_vm *vm);
+int panthor_vm_flush_all(struct panthor_vm *vm);
 
 struct panthor_heap_pool *
 panthor_vm_get_heap_pool(struct panthor_vm *vm, bool create);