From: Ilia Mirkin <imirkin@alum.mit.edu>
Date: Sun, 22 Apr 2018 17:47:12 -0400
Subject: drm/nouveau: fix temp/pwm visibility, skip hwmon when no sensors exist
Git-commit: 7a22c737faef99d6f75d7049c1a2f6f0fdefb1ec
Patch-mainline: v4.18-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

A NV34 GPU was seeing temp and pwm entries in hwmon, which would error
out when read. These should not have been visible, but also the whole
hwmon object should just not have been registered in the first place.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/nouveau/nouveau_hwmon.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/nouveau/nouveau_hwmon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_hwmon.c
@@ -327,7 +327,7 @@ nouveau_temp_is_visible(const void *data
 	struct nouveau_drm *drm = nouveau_drm((struct drm_device *)data);
 	struct nvkm_therm *therm = nvxx_therm(&drm->client.device);
 
-	if (therm && therm->attr_get && nvkm_therm_temp_get(therm) < 0)
+	if (!therm || !therm->attr_get || nvkm_therm_temp_get(therm) < 0)
 		return 0;
 
 	switch (attr) {
@@ -351,8 +351,8 @@ nouveau_pwm_is_visible(const void *data,
 	struct nouveau_drm *drm = nouveau_drm((struct drm_device *)data);
 	struct nvkm_therm *therm = nvxx_therm(&drm->client.device);
 
-	if (therm && therm->attr_get && therm->fan_get &&
-				therm->fan_get(therm) < 0)
+	if (!therm || !therm->attr_get || !therm->fan_get ||
+	    therm->fan_get(therm) < 0)
 		return 0;
 
 	switch (attr) {
@@ -707,13 +707,20 @@ nouveau_hwmon_init(struct drm_device *de
 {
 #if defined(CONFIG_HWMON) || (defined(MODULE) && defined(CONFIG_HWMON_MODULE))
 	struct nouveau_drm *drm = nouveau_drm(dev);
+	struct nvkm_iccsense *iccsense = nvxx_iccsense(&drm->client.device);
 	struct nvkm_therm *therm = nvxx_therm(&drm->client.device);
+	struct nvkm_volt *volt = nvxx_volt(&drm->client.device);
 	const struct attribute_group *special_groups[N_ATTR_GROUPS];
 	struct nouveau_hwmon *hwmon;
 	struct device *hwmon_dev;
 	int ret = 0;
 	int i = 0;
 
+	if (!iccsense && !therm && !volt) {
+		NV_DEBUG(drm, "Skipping hwmon registration\n");
+		return 0;
+	}
+
 	hwmon = drm->hwmon = kzalloc(sizeof(*hwmon), GFP_KERNEL);
 	if (!hwmon)
 		return -ENOMEM;
@@ -749,6 +756,9 @@ nouveau_hwmon_fini(struct drm_device *de
 #if defined(CONFIG_HWMON) || (defined(MODULE) && defined(CONFIG_HWMON_MODULE))
 	struct nouveau_hwmon *hwmon = nouveau_hwmon(dev);
 
+	if (!hwmon)
+		return;
+
 	if (hwmon->hwmon)
 		hwmon_device_unregister(hwmon->hwmon);