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From 37b556606d1217b4367e622d88cef11c65764386 Mon Sep 17 00:00:00 2001
From: Ben Skeggs <bskeggs@redhat.com>
Date: Tue, 31 Mar 2020 16:08:44 +1000
Subject: [PATCH 2/2] drm/nouveau/gr/gp107,gp108: implement workaround for HW
hanging during init
Certain boards with GP107/GP108 chipsets hang (often, but randomly) for
unknown reasons during GR initialisation.
The first tell-tale symptom of this issue is:
nouveau 0000:01:00.0: bus: MMIO read of 00000000 FAULT at 409800 [ TIMEOUT ]
appearing in dmesg, likely followed by many other failures being logged.
Karol found this WAR for the issue a while back, but efforts to isolate
the root cause and proper fix have not yielded success so far. I've
modified the original patch to include a few more details, limit it to
GP107/GP108 by default, and added a config option to override this choice.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
---
.../gpu/drm/nouveau/nvkm/engine/gr/gf100.c | 26 +++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/gr/gf100.c b/drivers/gpu/drm/nouveau/nvkm/engine/gr/gf100.c
index dd8f85b8b3a7..f2f5636efac4 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/gr/gf100.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/gr/gf100.c
@@ -1981,8 +1981,34 @@ gf100_gr_init_(struct nvkm_gr *base)
{
struct gf100_gr *gr = gf100_gr(base);
struct nvkm_subdev *subdev = &base->engine.subdev;
+ struct nvkm_device *device = subdev->device;
+ bool reset = device->chipset == 0x137 || device->chipset == 0x138;
u32 ret;
+ /* On certain GP107/GP108 boards, we trigger a weird issue where
+ * GR will stop responding to PRI accesses after we've asked the
+ * SEC2 RTOS to boot the GR falcons. This happens with far more
+ * frequency when cold-booting a board (ie. returning from D3).
+ *
+ * The root cause for this is not known and has proven difficult
+ * to isolate, with many avenues being dead-ends.
+ *
+ * A workaround was discovered by Karol, whereby putting GR into
+ * reset for an extended period right before initialisation
+ * prevents the problem from occuring.
+ *
+ * XXX: As RM does not require any such workaround, this is more
+ * of a hack than a true fix.
+ */
+ reset = nvkm_boolopt(device->cfgopt, "NvGrResetWar", reset);
+ if (reset) {
+ nvkm_mask(device, 0x000200, 0x00001000, 0x00000000);
+ nvkm_rd32(device, 0x000200);
+ msleep(50);
+ nvkm_mask(device, 0x000200, 0x00001000, 0x00001000);
+ nvkm_rd32(device, 0x000200);
+ }
+
nvkm_pmu_pgob(gr->base.engine.subdev.device->pmu, false);
ret = nvkm_falcon_get(&gr->fecs.falcon, subdev);
--
2.25.1
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