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From:   Jeremy Cline <jcline@redhat.com>
To:     Ben Skeggs <bskeggs@redhat.com>
Cc:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        Karol Herbst <kherbst@redhat.com>,
        dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, Jeremy Cline <jcline@redhat.com>
Subject: [PATCH] drm/nouveau: Add fine-grain temperature reporting
Date:   Wed, 12 Aug 2020 16:49:52 -0400
Message-Id: <20200812204952.1921587-1-jcline@redhat.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
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Commit d32656373857 ("drm/nouveau/therm/gp100: initial implementation of
new gp1xx temperature sensor") added support for reading finer-grain
temperatures, but continued to report temperatures in 1 degree Celsius
increments via nvkm_therm_temp_get().

Rather than altering nvkm_therm_temp_get() to report finer-grain
temperatures, which would be inconvenient for other users of the
function, a second interface has been added to line up with hwmon's
native unit of temperature.

Signed-off-by: Jeremy Cline <jcline@redhat.com>
---
 .../drm/nouveau/include/nvkm/subdev/therm.h   | 18 +++++++++++++
 drivers/gpu/drm/nouveau/nouveau_hwmon.c       |  4 +--
 .../gpu/drm/nouveau/nvkm/subdev/therm/base.c  | 16 ++++++++++++
 .../gpu/drm/nouveau/nvkm/subdev/therm/gp100.c | 25 +++++++++++++++++--
 .../gpu/drm/nouveau/nvkm/subdev/therm/priv.h  |  1 +
 5 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/include/nvkm/subdev/therm.h b/drivers/gpu/drm/nouveau/include/nvkm/subdev/therm.h
index 62c34f98c930..7b9928dd001c 100644
--- a/drivers/gpu/drm/nouveau/include/nvkm/subdev/therm.h
+++ b/drivers/gpu/drm/nouveau/include/nvkm/subdev/therm.h
@@ -100,6 +100,24 @@ struct nvkm_therm {
 };
 
 int nvkm_therm_temp_get(struct nvkm_therm *);
+
+/**
+ * nvkm_therm_temp_millidegree_get() - get the temperature in millidegrees
+ * @therm: The thermal device to read from.
+ *
+ * This interface reports temperatures in units of millidegree Celsius to
+ * align with the hwmon API. Some cards may only be capable of reporting in
+ * units of Celsius, and those that report finer grain temperatures may not be
+ * capable of millidegree Celsius accuracy,
+ *
+ * For cases where millidegree temperature is too fine-grain, the
+ * nvkm_therm_temp_get() interface reports temperatures in one degree Celsius
+ * increments.
+ *
+ * Return: The temperature in millidegrees Celsius, or -ENODEV if temperature
+ *         reporting is not supported.
+ */
+int nvkm_therm_temp_millidegree_get(struct nvkm_therm *therm);
 int nvkm_therm_fan_sense(struct nvkm_therm *);
 int nvkm_therm_cstate(struct nvkm_therm *, int, int);
 void nvkm_therm_clkgate_init(struct nvkm_therm *,
diff --git a/drivers/gpu/drm/nouveau/nouveau_hwmon.c b/drivers/gpu/drm/nouveau/nouveau_hwmon.c
index 1c3104d20571..e96355f93ce5 100644
--- a/drivers/gpu/drm/nouveau/nouveau_hwmon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_hwmon.c
@@ -428,8 +428,8 @@ nouveau_temp_read(struct device *dev, u32 attr, int channel, long *val)
 	case hwmon_temp_input:
 		if (drm_dev->switch_power_state != DRM_SWITCH_POWER_ON)
 			return -EINVAL;
-		ret = nvkm_therm_temp_get(therm);
-		*val = ret < 0 ? ret : (ret * 1000);
+		ret = nvkm_therm_temp_millidegree_get(therm);
+		*val = ret;
 		break;
 	case hwmon_temp_max:
 		*val = therm->attr_get(therm, NVKM_THERM_ATTR_THRS_DOWN_CLK)
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/base.c
index 4a4d1e224126..e655b32c78b8 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/base.c
@@ -34,6 +34,22 @@ nvkm_therm_temp_get(struct nvkm_therm *therm)
 	return -ENODEV;
 }
 
+int
+nvkm_therm_temp_millidegree_get(struct nvkm_therm *therm)
+{
+	int ret = -ENODEV;
+
+	if (therm->func->temp_millidegree_get)
+		return therm->func->temp_millidegree_get(therm);
+
+	if (therm->func->temp_get) {
+		ret = therm->func->temp_get(therm);
+		if (ret > 0)
+			ret *= 1000;
+	}
+	return ret;
+}
+
 static int
 nvkm_therm_update_trip(struct nvkm_therm *therm)
 {
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/gp100.c b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/gp100.c
index 9f0dea3f61dc..4c3c2895a3cb 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/gp100.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/gp100.c
@@ -24,7 +24,7 @@
 #include "priv.h"
 
 static int
-gp100_temp_get(struct nvkm_therm *therm)
+gp100_temp_get_raw(struct nvkm_therm *therm)
 {
 	struct nvkm_device *device = therm->subdev.device;
 	struct nvkm_subdev *subdev = &therm->subdev;
@@ -37,14 +37,35 @@ gp100_temp_get(struct nvkm_therm *therm)
 
 	/* device valid */
 	if (tsensor & 0x20000000)
-		return (inttemp >> 8);
+		return inttemp;
 	else
 		return -ENODEV;
 }
 
+static int
+gp100_temp_millidegree_get(struct nvkm_therm *therm)
+{
+	int raw_temp = gp100_temp_get_raw(therm);
+
+	if (raw_temp < 0)
+		return raw_temp;
+	return raw_temp * 1000 >> 8;
+}
+
+static int
+gp100_temp_get(struct nvkm_therm *therm)
+{
+	int raw_temp = gp100_temp_get_raw(therm);
+
+	if (raw_temp < 0)
+		return raw_temp;
+	return raw_temp >> 8;
+}
+
 static const struct nvkm_therm_func
 gp100_therm = {
 	.temp_get = gp100_temp_get,
+	.temp_millidegree_get = gp100_temp_millidegree_get,
 	.program_alarms = nvkm_therm_program_alarms_polling,
 };
 
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/priv.h b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/priv.h
index 21659daf1864..a53068b4f0b9 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/priv.h
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/priv.h
@@ -92,6 +92,7 @@ struct nvkm_therm_func {
 	int (*pwm_clock)(struct nvkm_therm *, int line);
 
 	int (*temp_get)(struct nvkm_therm *);
+	int (*temp_millidegree_get)(struct nvkm_therm *therm);
 
 	int (*fan_sense)(struct nvkm_therm *);
 
-- 
2.26.2