[PATCH 4.14 29/31] Revert "drm/nouveau/pmu/gm200-: avoid touching PMU outside of DEVINIT/PREOS/ACR"

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Karol Herbst <kherbst@redhat.com>

This reverts commit c9ec3d85c0eef7c71cdc68db758e0f0e378132c0.

This commit causes a regression if 4cdd2450bf739bada353e82d27b00db9af8c3001
is not applied as well. This was fixed for 5.16, 5.15 and 5.10.

On older stable branches backporting this commit is complicated as relevant
code changed quite a bit. Furthermore most of the affected hardware barely
works on those and users would want to use the newer kernels anyway.

Cc: stable@vger.kernel.org # 5.4 4.19 and 4.14
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Link: https://gitlab.freedesktop.org/drm/nouveau/-/issues/149
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c |   37 ++++++++++---------------
 1 file changed, 16 insertions(+), 21 deletions(-)

--- a/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c
@@ -70,13 +70,20 @@ nvkm_pmu_fini(struct nvkm_subdev *subdev
 	return 0;
 }
 
-static void
+static int
 nvkm_pmu_reset(struct nvkm_pmu *pmu)
 {
 	struct nvkm_device *device = pmu->subdev.device;
 
 	if (!pmu->func->enabled(pmu))
-		return;
+		return 0;
+
+	/* Inhibit interrupts, and wait for idle. */
+	nvkm_wr32(device, 0x10a014, 0x0000ffff);
+	nvkm_msec(device, 2000,
+		if (!nvkm_rd32(device, 0x10a04c))
+			break;
+	);
 
 	/* Reset. */
 	if (pmu->func->reset)
@@ -87,37 +94,25 @@ 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);
-	nvkm_pmu_reset(pmu);
-	return 0;
+	return nvkm_pmu_reset(pmu);
 }
 
 static int
 nvkm_pmu_init(struct nvkm_subdev *subdev)
 {
 	struct nvkm_pmu *pmu = nvkm_pmu(subdev);
-	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);
+	int ret = nvkm_pmu_reset(pmu);
+	if (ret == 0 && pmu->func->init)
+		ret = pmu->func->init(pmu);
+	return ret;
 }
 
 static int