drm/amdgpu: added a sysfs interface for thermal throttling related V4

User can check and set the enablement of throttling logging and
the interval between each logging.

V2: simplify the sysfs interface(no string parsing)
V3: add proper lock protection on updating throttling_logging_rs.interval
V4: documentation cosmetic per Luben's suggestion

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index 775e389c9a13..b0dff9ecfb88 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -1808,6 +1808,73 @@ static ssize_t amdgpu_get_unique_id(struct device *dev,
 	return 0;
 }
 
+/**
+ * DOC: thermal_throttling_logging
+ *
+ * Thermal throttling pulls down the clock frequency and thus the performance.
+ * It's an useful mechanism to protect the chip from overheating. Since it
+ * impacts performance, the user controls whether it is enabled and if so,
+ * the log frequency.
+ *
+ * Reading back the file shows you the status(enabled or disabled) and
+ * the interval(in seconds) between each thermal logging.
+ *
+ * Writing an integer to the file, sets a new logging interval, in seconds.
+ * The value should be between 1 and 3600. If the value is less than 1,
+ * thermal logging is disabled. Values greater than 3600 are ignored.
+ */
+static ssize_t amdgpu_get_thermal_throttling_logging(struct device *dev,
+						     struct device_attribute *attr,
+						     char *buf)
+{
+	struct drm_device *ddev = dev_get_drvdata(dev);
+	struct amdgpu_device *adev = ddev->dev_private;
+
+	return snprintf(buf, PAGE_SIZE, "%s: thermal throttling logging %s, with interval %d seconds\n",
+			adev->ddev->unique,
+			atomic_read(&adev->throttling_logging_enabled) ? "enabled" : "disabled",
+			adev->throttling_logging_rs.interval / HZ + 1);
+}
+
+static ssize_t amdgpu_set_thermal_throttling_logging(struct device *dev,
+						     struct device_attribute *attr,
+						     const char *buf,
+						     size_t count)
+{
+	struct drm_device *ddev = dev_get_drvdata(dev);
+	struct amdgpu_device *adev = ddev->dev_private;
+	long throttling_logging_interval;
+	unsigned long flags;
+	int ret = 0;
+
+	ret = kstrtol(buf, 0, &throttling_logging_interval);
+	if (ret)
+		return ret;
+
+	if (throttling_logging_interval > 3600)
+		return -EINVAL;
+
+	if (throttling_logging_interval > 0) {
+		raw_spin_lock_irqsave(&adev->throttling_logging_rs.lock, flags);
+		/*
+		 * Reset the ratelimit timer internals.
+		 * This can effectively restart the timer.
+		 */
+		adev->throttling_logging_rs.interval =
+			(throttling_logging_interval - 1) * HZ;
+		adev->throttling_logging_rs.begin = 0;
+		adev->throttling_logging_rs.printed = 0;
+		adev->throttling_logging_rs.missed = 0;
+		raw_spin_unlock_irqrestore(&adev->throttling_logging_rs.lock, flags);
+
+		atomic_set(&adev->throttling_logging_enabled, 1);
+	} else {
+		atomic_set(&adev->throttling_logging_enabled, 0);
+	}
+
+	return count;
+}
+
 static struct amdgpu_device_attr amdgpu_device_attrs[] = {
 	AMDGPU_DEVICE_ATTR_RW(power_dpm_state,				ATTR_FLAG_BASIC|ATTR_FLAG_ONEVF),
 	AMDGPU_DEVICE_ATTR_RW(power_dpm_force_performance_level,	ATTR_FLAG_BASIC|ATTR_FLAG_ONEVF),
@@ -1830,6 +1897,7 @@ static struct amdgpu_device_attr amdgpu_device_attrs[] = {
 	AMDGPU_DEVICE_ATTR_RO(pcie_bw,					ATTR_FLAG_BASIC),
 	AMDGPU_DEVICE_ATTR_RW(pp_features,				ATTR_FLAG_BASIC),
 	AMDGPU_DEVICE_ATTR_RO(unique_id,				ATTR_FLAG_BASIC),
+	AMDGPU_DEVICE_ATTR_RW(thermal_throttling_logging,		ATTR_FLAG_BASIC),
 };
 
 static int default_attr_update(struct amdgpu_device *adev, struct amdgpu_device_attr *attr,