From 176070da8ea247a8b29a8e4b36b169517d1bc36a Mon Sep 17 00:00:00 2001
From: Ben Skeggs <bskeggs@redhat.com>
Date: Wed, 24 Feb 2021 19:29:52 +1000
Subject: drm/nouveau/pmu/gm200-: avoid touching PMU outside of
 DEVINIT/PREOS/ACR
Git-commit: 1d2271d2fb85e54bfc9630a6c30ac0feb9ffb983
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

There have been reports of the WFI timing out on some boards, and a
patch was proposed to just remove it.  This stuff is rather fragile,
and I believe the WFI might be needed with our FW prior to GM200.

However, we probably should not be touching PMU during init on GPUs
where we depend on NVIDIA FW, outside of limited circumstances, so
this should be a somewhat safer change that achieves the desired
result.

Reported-by: Diego Viola <diego.viola@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://gitlab.freedesktop.org/drm/nouveau/-/merge_requests/10
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 .../gpu/drm/nouveau/nvkm/subdev/pmu/base.c    | 37 +++++++++++--------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c
index 24382875fb4f..455e95a89259 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c
@@ -94,20 +94,13 @@ nvkm_pmu_fini(struct nvkm_subdev *subdev, bool suspend)
 	return 0;
 }
 
-static int
+static void
 nvkm_pmu_reset(struct nvkm_pmu *pmu)
 {
 	struct nvkm_device *device = pmu->subdev.device;
 
 	if (!pmu->func->enabled(pmu))
-		return 0;
-
-	/* Inhibit interrupts, and wait for idle. */
-	nvkm_wr32(device, 0x10a014, 0x0000ffff);
-	nvkm_msec(device, 2000,
-		if (!nvkm_rd32(device, 0x10a04c))
-			break;
-	);
+		return;
 
 	/* Reset. */
 	if (pmu->func->reset)
@@ -118,25 +111,37 @@ nvkm_pmu_reset(struct nvkm_pmu *pmu)
 		if (!(nvkm_rd32(device, 0x10a10c) & 0x00000006))
 			break;
 	);
-
-	return 0;
 }
 
 static int
 nvkm_pmu_preinit(struct nvkm_subdev *subdev)
 {
 	struct nvkm_pmu *pmu = nvkm_pmu(subdev);
-	return nvkm_pmu_reset(pmu);
+	nvkm_pmu_reset(pmu);
+	return 0;
 }
 
 static int
 nvkm_pmu_init(struct nvkm_subdev *subdev)
 {
 	struct nvkm_pmu *pmu = nvkm_pmu(subdev);
-	int ret = nvkm_pmu_reset(pmu);
-	if (ret == 0 && pmu->func->init)
-		ret = pmu->func->init(pmu);
-	return ret;
+	struct nvkm_device *device = pmu->subdev.device;
+
+	if (!pmu->func->init)
+		return 0;
+
+	if (pmu->func->enabled(pmu)) {
+		/* Inhibit interrupts, and wait for idle. */
+		nvkm_wr32(device, 0x10a014, 0x0000ffff);
+		nvkm_msec(device, 2000,
+			if (!nvkm_rd32(device, 0x10a04c))
+				break;
+		);
+
+		nvkm_pmu_reset(pmu);
+	}
+
+	return pmu->func->init(pmu);
 }
 
 static void *
-- 
2.38.1