| Age | Commit message (Collapse) | Author |
|---|
|
Add debugfs interface to override hardware provide temperature. This
interface can be used primarily for debug. Alternatively this can
be also used to use hardware control loops to manage temperature for
virtual sensors. Virtual sensors are soft sensors created by kernel/
user space aggregating other sensors.
There are three attributes to override the maximum three instances of
platform temperature control.
/sys/kernel/debug/platform_temperature_control/
├── temperature_0
├── temperature_1
└── temperature_2
These are write only attributes requires admin privilege. Any value
greater than 0, will override the temperature. A value of 0 will
stop overriding the temperature.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Link: https://patch.msgid.link/20250613214923.2910397-2-srinivas.pandruvada@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
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@linux.intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Link: https://patch.msgid.link/20250613214923.2910397-1-srinivas.pandruvada@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Platform Temperature Control is a dynamic control loop implemented in
hardware to manage the skin or any board temperature of a device. The
reported skin or board temperature is controlled by comparing to a
configured target temperature and adjusting the SoC (System on Chip)
performance accordingly. The feature supports up to three platform
sensors.
OEMs (Original Equipment Manufacturers) can configure this feature
through the BIOS and provide temperature input directly to the hardware
via the Platform Environment Control Interface (PECI). As a result,
this feature can operate independently of any OS-level control.
The OS interface can be used to further fine-tune the default OEM
configuration. Here are some scenarios where the OS interface is
beneficial:
Verification of Firmware Control: Check if firmware-based control is
enabled. If it is, thermal controls from the OS/user space can be
backed out.
Adjusting Target Limits: While OEMs can set an aggressive target limit,
the OS can adjust this to a less aggressive limit based on operating
modes or conditions.
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
can lead to unexpected behavior. For instance, on a Linux desktop, the
Linux thermal daemon can manage these temperature controls, as it has
access to all other temperature control settings.
The hardware control interface is via MMIO offsets in the processor
thermal device MMIO space. There are three instances of MMIO registers.
Refer to the platform_temperature_control.c for MMIO details.
Expose "enable" and "temperature_target" via sysfs.
There are three instances of this controls. So up to three different
sensors can be controlled independently.
Sysfs interface:
tree /sys/bus/pci/devices/0000\:00\:04.0/ptc_?_control/
/sys/bus/pci/devices/0000:00:04.0/ptc_0_control/
├── enable
└── temperature_target
/sys/bus/pci/devices/0000:00:04.0/ptc_1_control/
├── enable
└── temperature_target
/sys/bus/pci/devices/0000:00:04.0/ptc_2_control/
├── enable
└── temperature_target
Description of attributes:
Enable: 1 for enable, 0 for disable. This attribute can be used to
read the current status. User space can write 0 or 1 to disable or
enable this feature respectively.
temperature_target: Target temperature limit to which hardware
will try to limit in milli degree C.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20250429000110.236243-2-srinivas.pandruvada@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
