linux-kernel - [PATCH v2 1/2] thermal: intel: int340x: Add throttling control interface to PTC

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Message-ID: <20250613214923.2910397-1-srinivas.pandruvada@linux.intel.com>
Date: Fri, 13 Jun 2025 14:49:22 -0700
From: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To: rui.zhang@...el.com,
	daniel.lezcano@...aro.org,
	rafael@...nel.org,
	lukasz.luba@....com
Cc: linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: [PATCH v2 1/2] thermal: intel: int340x: Add throttling control interface to PTC

Firmware-based thermal temperature control loops may aggressively
throttle performance to prevent temperature overshoots relative to the
defined target temperature. This can negatively impact performance. User
space may prefer to prioritize performance, even if it results in
temperature overshoots with in acceptable range.

For example, user space might tolerate temperature overshoots when the
device is placed on a desk, as opposed to when it's on a lap. To
accommodate such scenarios, an optional attribute is provided to specify
a tolerance level for temperature overshoots while maintaining acceptable
performance.

Attribute:
thermal_tolerance: This attribute ranges from 0 to 7, where 0 represents
the most aggressive control to avoid any temperature overshoots, and 7
represents a more graceful approach, favoring performance even at the
expense of temperature overshoots.
Note: This level may not scale linearly. For example, a value of 3 does not
necessarily imply a 50% improvement in performance compared to a value of
0.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
---
v2:
- Changed commit description
- Change "gain" to "thermal_tolerance" analogous to latency_tolerance.
- Dropped "min_performance" attribute for next patch set

 Documentation/driver-api/thermal/intel_dptf.rst          | 9 +++++++++
 .../intel/int340x_thermal/platform_temperature_control.c | 8 +++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/Documentation/driver-api/thermal/intel_dptf.rst b/Documentation/driver-api/thermal/intel_dptf.rst
index ec5769accae0..c51ac793dc06 100644
--- a/Documentation/driver-api/thermal/intel_dptf.rst
+++ b/Documentation/driver-api/thermal/intel_dptf.rst
@@ -206,6 +206,15 @@ All these controls needs admin privilege to update.
 	Update a new temperature target in milli degree celsius for hardware to
 	use for the temperature control.
 
+``thermal_tolerance`` (RW)
+	This attribute ranges from 0 to 7, where 0 represents
+	the most aggressive control to avoid any temperature overshoots, and
+	7 represents a more graceful approach, favoring performance even at
+	the expense of temperature overshoots.
+	Note: This level may not scale linearly. For example, a value of 3 does
+	not necessarily imply a 50% improvement in performance compared to a
+	value of 0.
+
 Given that this is platform temperature control, it is expected that a
 single user-level manager owns and manages the controls. If multiple
 user-level software applications attempt to write different targets, it
diff --git a/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c b/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c
index 2d6504514893..7850e91a6e2c 100644
--- a/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c
+++ b/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c
@@ -49,7 +49,7 @@ struct mmio_reg {
 };
 
 #define MAX_ATTR_GROUP_NAME_LEN	32
-#define PTC_MAX_ATTRS		3
+#define PTC_MAX_ATTRS		4
 
 struct ptc_data {
 	u32 offset;
@@ -57,6 +57,7 @@ struct ptc_data {
 	struct attribute *ptc_attrs[PTC_MAX_ATTRS];
 	struct device_attribute temperature_target_attr;
 	struct device_attribute enable_attr;
+	struct device_attribute thermal_tolerance_attr;
 	char group_name[MAX_ATTR_GROUP_NAME_LEN];
 };
 
@@ -78,6 +79,7 @@ static u32 ptc_offsets[PTC_MAX_INSTANCES] = {0x5B20, 0x5B28, 0x5B30};
 static const char * const ptc_strings[] = {
 	"temperature_target",
 	"enable",
+	"thermal_tolerance",
 	NULL
 };
 
@@ -177,6 +179,8 @@ PTC_SHOW(temperature_target);
 PTC_STORE(temperature_target);
 PTC_SHOW(enable);
 PTC_STORE(enable);
+PTC_SHOW(thermal_tolerance);
+PTC_STORE(thermal_tolerance);
 
 #define ptc_init_attribute(_name)\
 	do {\
@@ -193,9 +197,11 @@ static int ptc_create_groups(struct pci_dev *pdev, int instance, struct ptc_data
 
 	ptc_init_attribute(temperature_target);
 	ptc_init_attribute(enable);
+	ptc_init_attribute(thermal_tolerance);
 
 	data->ptc_attrs[index++] = &data->temperature_target_attr.attr;
 	data->ptc_attrs[index++] = &data->enable_attr.attr;
+	data->ptc_attrs[index++] = &data->thermal_tolerance_attr.attr;
 	data->ptc_attrs[index] = NULL;
 
 	snprintf(data->group_name, MAX_ATTR_GROUP_NAME_LEN,
-- 
2.49.0