For thermal management strategy you might be interested on limit the
input power for a power supply. We already have current limit but
basically what we probably want is to limit power. So, introduce the
input_power_limit property.
Although the common use case is limit the input power, in some
specific cases it is the voltage that is problematic (i.e some regulators
have different efficiencies at higher voltage resulting in more heat).
So introduce also the input_voltage_limit property.
This happens in one Chromebook and is used on the Pixel C's thermal
management strategy to effectively limit the input power to 5V 3A when
the screen is on. When the screen is on, the display, the CPU, and the GPU
all contribute more heat to the system than while the screen is off, and
we made a tradeoff to throttle the charger in order to give more of the
thermal budget to those other components.
So there's nothing fundamentally broken about the hardware that would
cause the Pixel C to malfunction if we were charging at 9V or 12V instead
of 5V when the screen is on, i.e. if userspace doesn't change this.
What would happen is that you wouldn't meet Google's skin temperature
targets on the system if the charger was allowed to run at 9V or 12V with
the screen on.
For folks hacking on Pixel Cs (which is now outside of Google's official
support window for Android) and customizing their own kernel and userspace
this would be acceptable, but we wanted to expose this feature in the
power supply properties because the feature does exist in the Emedded
Controller firmware of the Pixel C and all of Google's Chromebooks with
USB-C made since 2015 in case someone running an up to date kernel wanted
to limit the charging power for thermal or other reasons.
This patch exposes a new property, similar to input current limit, to
re-configure the maximum voltage from the external supply at runtime
based on system-level knowledge or user input.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Acked-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
The existing POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT and
POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX properties
don't have documentation. I add that documentation here.
v5 changes:
- Split this commit out from the previous two commits.
Signed-off-by: Nick Crews <ncrews@chromium.org>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Add POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD
and POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD properties, to expand
the existing CHARGE_CONTROL_* properties. I am adding them in order
to support a new Chrome OS device, but these properties should be
general enough that they can be used on other devices.
When the charge_type is "Custom", the charge controller uses the
POWER_SUPPLY_PROP_CHARGE_CONTROL_* properties as configuration for some
other algorithm. For example, in the use case that I am supporting,
this means the battery begins charging when the percentage
level drops below POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD and
charging ceases when the percentage level goes above
POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD.
v5 changes:
- Add the other missing CHARGE_CONTROL_* properties documentation in
a separate commit
- Split up adding the charge types and adding the
POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD and
POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD properties into
two different commits.
v4 changes:
- Add documentation for the new properties, and add documentation for
the the previously missing charge_control_limit and
charge_control_limit_max properties.
Signed-off-by: Nick Crews <ncrews@chromium.org>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Add "Standard", "Adaptive", and "Custom" modes to the charge_type
property, to expand the existing "Trickle" and "Fast" modes.
I am adding them in order to support a new Chrome OS device,
but these properties should be general enough that they can be
used on other devices.
The meaning of "Standard" is obvious, but "Adaptive" and "Custom" are
more tricky: "Adaptive" means that the charge controller uses some
custom algorithm to change the charge type automatically, with no
configuration needed. "Custom" means that the charge controller uses the
POWER_SUPPLY_PROP_CHARGE_CONTROL_* properties as configuration for some
other algorithm.
v5 changes:
- Split up adding the charge types and adding the
POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD and
POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD properties into
two different commits.
v4 changes:
- Add documentation for the new properties, and add documentation for
the the previously missing charge_control_limit and
charge_control_limit_max properties.
Signed-off-by: Nick Crews <ncrews@chromium.org>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
This commit adds the 'usb_type' property to represent USB supplies
which can report a number of different types based on a connection
event.
Examples of this already exist in drivers whereby the existing 'type'
property is updated, based on an event, to represent what was
connected (e.g. USB, USB_DCP, USB_ACA, ...). Current implementations
however don't show all supported connectable types, so this knowledge
has to be exlicitly known for each driver that supports this.
The 'usb_type' property is intended to fill this void and show users
all possible USB types supported by a driver. The property, when read,
shows all available types for the driver, and the one currently chosen
is highlighted/bracketed. It is expected that the 'type' property
would then just show the top-level type 'USB', and this would be
static.
Currently the 'usb_type' enum contains all of the USB variant types
that exist for the 'type' enum at this time, and in addition has
SDP and PPS types. The mirroring is intentional so as to not impact
existing usage of the 'type' property.
Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit adds generic ABI information regarding power_supply
properties. This is an initial attempt to try and align the usage
of these properties between drivers. As part of this commit,
common Battery and USB related properties have been listed.
Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change my email address to kernel.org instead of Samsung one for the
purpose of any future contact. The copyrights remain untouched and are
attributed to Samsung.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Document the settings exported by max77693 charger driver through sysfs
entries:
- fast_charge_timer
- top_off_threshold_current
- top_off_timer
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Update the date of introducing max14577 charger's ABI (fast_charge_timer
sysfs entry) to approximate date of kernel release which actually
introduces this.
The old date came from previous driver submissions.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Document the 'fast charge timer' setting exported by max14577 driver
through sysfs entry.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Add some documentation for the newly added writeable properties.
Suggested-by: Greg KH <gregkh@suse.de>
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
