drm/nouveau/nvif: protect waits against GPU falling off the bus

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nouveau/nvif/timer.c b/drivers/gpu/drm/nouveau/nvif/timer.c
new file mode 100644
index 000000000000..602c1a258d10
--- /dev/null
+++ b/drivers/gpu/drm/nouveau/nvif/timer.c
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2020 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include <nvif/timer.h>
+#include <nvif/device.h>
+
+s64
+nvif_timer_wait_test(struct nvif_timer_wait *wait)
+{
+	u64 time = nvif_device_time(wait->device);
+
+	if (wait->reads == 0) {
+		wait->time0 = time;
+		wait->time1 = time;
+	}
+
+	if (wait->time1 == time) {
+		if (WARN_ON(wait->reads++ == 16))
+			return -ETIMEDOUT;
+	} else {
+		wait->time1 = time;
+		wait->reads = 1;
+	}
+
+	if (wait->time1 - wait->time0 > wait->limit)
+		return -ETIMEDOUT;
+
+	return wait->time1 - wait->time0;
+}
+
+void
+nvif_timer_wait_init(struct nvif_device *device, u64 nsec,
+		     struct nvif_timer_wait *wait)
+{
+	wait->device = device;
+	wait->limit = nsec;
+	wait->reads = 0;
+}