* [PATCH v4 1/2] power: supply: add input power and voltage limit properties
@ 2019-05-07 9:52 Enric Balletbo i Serra
2019-05-07 9:52 ` Enric Balletbo i Serra
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Enric Balletbo i Serra @ 2019-05-07 9:52 UTC (permalink / raw)
To: linux-pm, sre
Cc: Sameer Nanda, bleung, rjw, gwendal, linux-kernel, Len Brown,
groeck, Adam.Thomson.Opensource, kernel, Pavel Machek
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>
---
Changes in v4:
- Add also input_power_limit.
Changes in v3:
- Improve commit log and documentation with Benson comments.
Changes in v2:
- Document the new property in ABI/testing/sysfs-class-power.
- Add the Reviewed-by Guenter Roeck tag.
Documentation/ABI/testing/sysfs-class-power | 32 +++++++++++++++++++++
Documentation/power/power_supply_class.txt | 4 +++
drivers/power/supply/power_supply_sysfs.c | 2 ++
include/linux/power_supply.h | 2 ++
4 files changed, 40 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
index 5e23e22dce1b..962a27a1daf8 100644
--- a/Documentation/ABI/testing/sysfs-class-power
+++ b/Documentation/ABI/testing/sysfs-class-power
@@ -331,10 +331,42 @@ Description:
supply. Normally this is configured based on the type of
connection made (e.g. A configured SDP should output a maximum
of 500mA so the input current limit is set to the same value).
+ Use preferably input_power_limit, and for problems that can be
+ solved using power limit use input_current_limit.
Access: Read, Write
Valid values: Represented in microamps
+What: /sys/class/power_supply/<supply_name>/input_voltage_limit
+Date: May 2019
+Contact: linux-pm@vger.kernel.org
+Description:
+ This entry configures the incoming VBUS voltage limit currently
+ set in the supply. Normally this is configured based on
+ system-level knowledge or user input (e.g. This is part of the
+ Pixel C's thermal management strategy to effectively limit the
+ input power to 5V when the screen is on to meet Google's skin
+ temperature targets). Note that this feature should not be
+ used for safety critical things.
+ Use preferably input_power_limit, and for problems that can be
+ solved using power limit use input_voltage_limit.
+
+ Access: Read, Write
+ Valid values: Represented in microvolts
+
+What: /sys/class/power_supply/<supply_name>/input_power_limit
+Date: May 2019
+Contact: linux-pm@vger.kernel.org
+Description:
+ This entry configures the incoming power limit currently set
+ in the supply. Normally this is configured based on
+ system-level knowledge or user input. Use preferably this
+ feature to limit the incoming power and use current/voltage
+ limit only for problems that can be solved using power limit.
+
+ Access: Read, Write
+ Valid values: Represented in microwatts
+
What: /sys/class/power_supply/<supply_name>/online,
Date: May 2007
Contact: linux-pm@vger.kernel.org
diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt
index 300d37896e51..1e3c705111db 100644
--- a/Documentation/power/power_supply_class.txt
+++ b/Documentation/power/power_supply_class.txt
@@ -137,6 +137,10 @@ power supply object.
INPUT_CURRENT_LIMIT - input current limit programmed by charger. Indicates
the current drawn from a charging source.
+INPUT_VOLTAGE_LIMIT - input voltage limit programmed by charger. Indicates
+the voltage limit from a charging source.
+INPUT_POWER_LIMIT - input power limit programmed by charger. Indicates
+the power limit from a charging source.
CHARGE_CONTROL_LIMIT - current charge control limit setting
CHARGE_CONTROL_LIMIT_MAX - maximum charge control limit setting
diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
index 5358a80d854f..860db617d241 100644
--- a/drivers/power/supply/power_supply_sysfs.c
+++ b/drivers/power/supply/power_supply_sysfs.c
@@ -275,6 +275,8 @@ static struct device_attribute power_supply_attrs[] = {
POWER_SUPPLY_ATTR(charge_control_limit),
POWER_SUPPLY_ATTR(charge_control_limit_max),
POWER_SUPPLY_ATTR(input_current_limit),
+ POWER_SUPPLY_ATTR(input_voltage_limit),
+ POWER_SUPPLY_ATTR(input_power_limit),
POWER_SUPPLY_ATTR(energy_full_design),
POWER_SUPPLY_ATTR(energy_empty_design),
POWER_SUPPLY_ATTR(energy_full),
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index 2f9c201a54d1..ba135a5d8996 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -122,6 +122,8 @@ enum power_supply_property {
POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT,
POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX,
POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
+ POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT,
+ POWER_SUPPLY_PROP_INPUT_POWER_LIMIT,
POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN,
POWER_SUPPLY_PROP_ENERGY_FULL,
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v4 1/2] power: supply: add input power and voltage limit properties
2019-05-07 9:52 [PATCH v4 1/2] power: supply: add input power and voltage limit properties Enric Balletbo i Serra
@ 2019-05-07 9:52 ` Enric Balletbo i Serra
2019-05-07 9:52 ` [PATCH v4 2/2] power: supply: cros: allow to set input voltage and current limit Enric Balletbo i Serra
2019-05-23 19:54 ` [PATCH v4 1/2] power: supply: add input power and voltage limit properties Benson Leung
2 siblings, 0 replies; 7+ messages in thread
From: Enric Balletbo i Serra @ 2019-05-07 9:52 UTC (permalink / raw)
To: linux-pm, sre
Cc: Sameer Nanda, bleung, rjw, gwendal, linux-kernel, Len Brown,
groeck, Adam.Thomson.Opensource, kernel, Pavel Machek
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>
---
Changes in v4:
- Add also input_power_limit.
Changes in v3:
- Improve commit log and documentation with Benson comments.
Changes in v2:
- Document the new property in ABI/testing/sysfs-class-power.
- Add the Reviewed-by Guenter Roeck tag.
Documentation/ABI/testing/sysfs-class-power | 32 +++++++++++++++++++++
Documentation/power/power_supply_class.txt | 4 +++
drivers/power/supply/power_supply_sysfs.c | 2 ++
include/linux/power_supply.h | 2 ++
4 files changed, 40 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
index 5e23e22dce1b..962a27a1daf8 100644
--- a/Documentation/ABI/testing/sysfs-class-power
+++ b/Documentation/ABI/testing/sysfs-class-power
@@ -331,10 +331,42 @@ Description:
supply. Normally this is configured based on the type of
connection made (e.g. A configured SDP should output a maximum
of 500mA so the input current limit is set to the same value).
+ Use preferably input_power_limit, and for problems that can be
+ solved using power limit use input_current_limit.
Access: Read, Write
Valid values: Represented in microamps
+What: /sys/class/power_supply/<supply_name>/input_voltage_limit
+Date: May 2019
+Contact: linux-pm@vger.kernel.org
+Description:
+ This entry configures the incoming VBUS voltage limit currently
+ set in the supply. Normally this is configured based on
+ system-level knowledge or user input (e.g. This is part of the
+ Pixel C's thermal management strategy to effectively limit the
+ input power to 5V when the screen is on to meet Google's skin
+ temperature targets). Note that this feature should not be
+ used for safety critical things.
+ Use preferably input_power_limit, and for problems that can be
+ solved using power limit use input_voltage_limit.
+
+ Access: Read, Write
+ Valid values: Represented in microvolts
+
+What: /sys/class/power_supply/<supply_name>/input_power_limit
+Date: May 2019
+Contact: linux-pm@vger.kernel.org
+Description:
+ This entry configures the incoming power limit currently set
+ in the supply. Normally this is configured based on
+ system-level knowledge or user input. Use preferably this
+ feature to limit the incoming power and use current/voltage
+ limit only for problems that can be solved using power limit.
+
+ Access: Read, Write
+ Valid values: Represented in microwatts
+
What: /sys/class/power_supply/<supply_name>/online,
Date: May 2007
Contact: linux-pm@vger.kernel.org
diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt
index 300d37896e51..1e3c705111db 100644
--- a/Documentation/power/power_supply_class.txt
+++ b/Documentation/power/power_supply_class.txt
@@ -137,6 +137,10 @@ power supply object.
INPUT_CURRENT_LIMIT - input current limit programmed by charger. Indicates
the current drawn from a charging source.
+INPUT_VOLTAGE_LIMIT - input voltage limit programmed by charger. Indicates
+the voltage limit from a charging source.
+INPUT_POWER_LIMIT - input power limit programmed by charger. Indicates
+the power limit from a charging source.
CHARGE_CONTROL_LIMIT - current charge control limit setting
CHARGE_CONTROL_LIMIT_MAX - maximum charge control limit setting
diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
index 5358a80d854f..860db617d241 100644
--- a/drivers/power/supply/power_supply_sysfs.c
+++ b/drivers/power/supply/power_supply_sysfs.c
@@ -275,6 +275,8 @@ static struct device_attribute power_supply_attrs[] = {
POWER_SUPPLY_ATTR(charge_control_limit),
POWER_SUPPLY_ATTR(charge_control_limit_max),
POWER_SUPPLY_ATTR(input_current_limit),
+ POWER_SUPPLY_ATTR(input_voltage_limit),
+ POWER_SUPPLY_ATTR(input_power_limit),
POWER_SUPPLY_ATTR(energy_full_design),
POWER_SUPPLY_ATTR(energy_empty_design),
POWER_SUPPLY_ATTR(energy_full),
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index 2f9c201a54d1..ba135a5d8996 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -122,6 +122,8 @@ enum power_supply_property {
POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT,
POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX,
POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
+ POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT,
+ POWER_SUPPLY_PROP_INPUT_POWER_LIMIT,
POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN,
POWER_SUPPLY_PROP_ENERGY_FULL,
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v4 2/2] power: supply: cros: allow to set input voltage and current limit
2019-05-07 9:52 [PATCH v4 1/2] power: supply: add input power and voltage limit properties Enric Balletbo i Serra
2019-05-07 9:52 ` Enric Balletbo i Serra
@ 2019-05-07 9:52 ` Enric Balletbo i Serra
2019-05-07 9:52 ` Enric Balletbo i Serra
2019-05-23 19:54 ` [PATCH v4 1/2] power: supply: add input power and voltage limit properties Benson Leung
2 siblings, 1 reply; 7+ messages in thread
From: Enric Balletbo i Serra @ 2019-05-07 9:52 UTC (permalink / raw)
To: linux-pm, sre
Cc: Sameer Nanda, bleung, rjw, gwendal, linux-kernel, Len Brown,
groeck, Adam.Thomson.Opensource, kernel, Pavel Machek
This patch allows reading and writing the input voltage and current
limit through the POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT and
POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT sysfs properties. This allows
userspace to see current values and to re-configure these values at
runtime based on system-level knowledge or user input.
By default there is no limit, this is reported as a -1 when reading from
userspace. Writing a value will set the current or voltage limit in uA
or uV, and writing any negative value will remove that limit.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
---
Changes in v4: None
Changes in v3: None
Changes in v2:
- Fix the upper limit that can be set.
- Remove unnecessary else.
drivers/power/supply/cros_usbpd-charger.c | 116 ++++++++++++++++++++++
1 file changed, 116 insertions(+)
diff --git a/drivers/power/supply/cros_usbpd-charger.c b/drivers/power/supply/cros_usbpd-charger.c
index 7e9c3984ef6a..3a9ea94c3de3 100644
--- a/drivers/power/supply/cros_usbpd-charger.c
+++ b/drivers/power/supply/cros_usbpd-charger.c
@@ -53,6 +53,8 @@ struct charger_data {
};
static enum power_supply_property cros_usbpd_charger_props[] = {
+ POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
+ POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT,
POWER_SUPPLY_PROP_ONLINE,
POWER_SUPPLY_PROP_STATUS,
POWER_SUPPLY_PROP_CURRENT_MAX,
@@ -80,6 +82,10 @@ static enum power_supply_usb_type cros_usbpd_charger_usb_types[] = {
POWER_SUPPLY_USB_TYPE_APPLE_BRICK_ID
};
+/* Input voltage/current limit in mV/mA. Default to none. */
+static u16 input_voltage_limit = EC_POWER_LIMIT_NONE;
+static u16 input_current_limit = EC_POWER_LIMIT_NONE;
+
static bool cros_usbpd_charger_port_is_dedicated(struct port_data *port)
{
return port->port_number >= port->charger->num_usbpd_ports;
@@ -324,6 +330,26 @@ static int cros_usbpd_charger_get_port_status(struct port_data *port,
return ret;
}
+static int cros_usbpd_charger_set_ext_power_limit(struct charger_data *charger,
+ u16 current_lim,
+ u16 voltage_lim)
+{
+ struct ec_params_external_power_limit_v1 req;
+ int ret;
+
+ req.current_lim = current_lim;
+ req.voltage_lim = voltage_lim;
+
+ ret = cros_usbpd_charger_ec_command(charger, 0,
+ EC_CMD_EXTERNAL_POWER_LIMIT,
+ &req, sizeof(req), NULL, 0);
+ if (ret < 0)
+ dev_err(charger->dev,
+ "Unable to set the 'External Power Limit': %d\n", ret);
+
+ return ret;
+}
+
static void cros_usbpd_charger_power_changed(struct power_supply *psy)
{
struct port_data *port = power_supply_get_drvdata(psy);
@@ -396,6 +422,18 @@ static int cros_usbpd_charger_get_prop(struct power_supply *psy,
case POWER_SUPPLY_PROP_USB_TYPE:
val->intval = port->psy_usb_type;
break;
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ if (input_current_limit == EC_POWER_LIMIT_NONE)
+ val->intval = -1;
+ else
+ val->intval = input_current_limit * 1000;
+ break;
+ case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+ if (input_voltage_limit == EC_POWER_LIMIT_NONE)
+ val->intval = -1;
+ else
+ val->intval = input_voltage_limit * 1000;
+ break;
case POWER_SUPPLY_PROP_MODEL_NAME:
val->strval = port->model_name;
break;
@@ -409,6 +447,81 @@ static int cros_usbpd_charger_get_prop(struct power_supply *psy,
return 0;
}
+static int cros_usbpd_charger_set_prop(struct power_supply *psy,
+ enum power_supply_property psp,
+ const union power_supply_propval *val)
+{
+ struct port_data *port = power_supply_get_drvdata(psy);
+ struct charger_data *charger = port->charger;
+ struct device *dev = charger->dev;
+ u16 intval;
+ int ret;
+
+ /* U16_MAX in mV/mA is the maximum supported value */
+ if (val->intval >= U16_MAX * 1000)
+ return -EINVAL;
+ /* A negative number is used to clear the limit */
+ if (val->intval < 0)
+ intval = EC_POWER_LIMIT_NONE;
+ else /* Convert from uA/uV to mA/mV */
+ intval = val->intval / 1000;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ ret = cros_usbpd_charger_set_ext_power_limit(charger, intval,
+ input_voltage_limit);
+ if (ret < 0)
+ break;
+
+ input_current_limit = intval;
+ if (input_current_limit == EC_POWER_LIMIT_NONE)
+ dev_info(dev,
+ "External Current Limit cleared for all ports\n");
+ else
+ dev_info(dev,
+ "External Current Limit set to %dmA for all ports\n",
+ input_current_limit);
+ break;
+ case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+ ret = cros_usbpd_charger_set_ext_power_limit(charger,
+ input_current_limit,
+ intval);
+ if (ret < 0)
+ break;
+
+ input_voltage_limit = intval;
+ if (input_voltage_limit == EC_POWER_LIMIT_NONE)
+ dev_info(dev,
+ "External Voltage Limit cleared for all ports\n");
+ else
+ dev_info(dev,
+ "External Voltage Limit set to %dmV for all ports\n",
+ input_voltage_limit);
+ break;
+ default:
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static int cros_usbpd_charger_property_is_writeable(struct power_supply *psy,
+ enum power_supply_property psp)
+{
+ int ret;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+ ret = 1;
+ break;
+ default:
+ ret = 0;
+ }
+
+ return ret;
+}
+
static int cros_usbpd_charger_ec_event(struct notifier_block *nb,
unsigned long queued_during_suspend,
void *_notify)
@@ -525,6 +638,9 @@ static int cros_usbpd_charger_probe(struct platform_device *pd)
psy_desc = &port->psy_desc;
psy_desc->get_property = cros_usbpd_charger_get_prop;
+ psy_desc->set_property = cros_usbpd_charger_set_prop;
+ psy_desc->property_is_writeable =
+ cros_usbpd_charger_property_is_writeable;
psy_desc->external_power_changed =
cros_usbpd_charger_power_changed;
psy_cfg.drv_data = port;
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v4 2/2] power: supply: cros: allow to set input voltage and current limit
2019-05-07 9:52 ` [PATCH v4 2/2] power: supply: cros: allow to set input voltage and current limit Enric Balletbo i Serra
@ 2019-05-07 9:52 ` Enric Balletbo i Serra
0 siblings, 0 replies; 7+ messages in thread
From: Enric Balletbo i Serra @ 2019-05-07 9:52 UTC (permalink / raw)
To: linux-pm, sre
Cc: Sameer Nanda, bleung, rjw, gwendal, linux-kernel, Len Brown,
groeck, Adam.Thomson.Opensource, kernel, Pavel Machek
This patch allows reading and writing the input voltage and current
limit through the POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT and
POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT sysfs properties. This allows
userspace to see current values and to re-configure these values at
runtime based on system-level knowledge or user input.
By default there is no limit, this is reported as a -1 when reading from
userspace. Writing a value will set the current or voltage limit in uA
or uV, and writing any negative value will remove that limit.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
---
Changes in v4: None
Changes in v3: None
Changes in v2:
- Fix the upper limit that can be set.
- Remove unnecessary else.
drivers/power/supply/cros_usbpd-charger.c | 116 ++++++++++++++++++++++
1 file changed, 116 insertions(+)
diff --git a/drivers/power/supply/cros_usbpd-charger.c b/drivers/power/supply/cros_usbpd-charger.c
index 7e9c3984ef6a..3a9ea94c3de3 100644
--- a/drivers/power/supply/cros_usbpd-charger.c
+++ b/drivers/power/supply/cros_usbpd-charger.c
@@ -53,6 +53,8 @@ struct charger_data {
};
static enum power_supply_property cros_usbpd_charger_props[] = {
+ POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
+ POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT,
POWER_SUPPLY_PROP_ONLINE,
POWER_SUPPLY_PROP_STATUS,
POWER_SUPPLY_PROP_CURRENT_MAX,
@@ -80,6 +82,10 @@ static enum power_supply_usb_type cros_usbpd_charger_usb_types[] = {
POWER_SUPPLY_USB_TYPE_APPLE_BRICK_ID
};
+/* Input voltage/current limit in mV/mA. Default to none. */
+static u16 input_voltage_limit = EC_POWER_LIMIT_NONE;
+static u16 input_current_limit = EC_POWER_LIMIT_NONE;
+
static bool cros_usbpd_charger_port_is_dedicated(struct port_data *port)
{
return port->port_number >= port->charger->num_usbpd_ports;
@@ -324,6 +330,26 @@ static int cros_usbpd_charger_get_port_status(struct port_data *port,
return ret;
}
+static int cros_usbpd_charger_set_ext_power_limit(struct charger_data *charger,
+ u16 current_lim,
+ u16 voltage_lim)
+{
+ struct ec_params_external_power_limit_v1 req;
+ int ret;
+
+ req.current_lim = current_lim;
+ req.voltage_lim = voltage_lim;
+
+ ret = cros_usbpd_charger_ec_command(charger, 0,
+ EC_CMD_EXTERNAL_POWER_LIMIT,
+ &req, sizeof(req), NULL, 0);
+ if (ret < 0)
+ dev_err(charger->dev,
+ "Unable to set the 'External Power Limit': %d\n", ret);
+
+ return ret;
+}
+
static void cros_usbpd_charger_power_changed(struct power_supply *psy)
{
struct port_data *port = power_supply_get_drvdata(psy);
@@ -396,6 +422,18 @@ static int cros_usbpd_charger_get_prop(struct power_supply *psy,
case POWER_SUPPLY_PROP_USB_TYPE:
val->intval = port->psy_usb_type;
break;
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ if (input_current_limit == EC_POWER_LIMIT_NONE)
+ val->intval = -1;
+ else
+ val->intval = input_current_limit * 1000;
+ break;
+ case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+ if (input_voltage_limit == EC_POWER_LIMIT_NONE)
+ val->intval = -1;
+ else
+ val->intval = input_voltage_limit * 1000;
+ break;
case POWER_SUPPLY_PROP_MODEL_NAME:
val->strval = port->model_name;
break;
@@ -409,6 +447,81 @@ static int cros_usbpd_charger_get_prop(struct power_supply *psy,
return 0;
}
+static int cros_usbpd_charger_set_prop(struct power_supply *psy,
+ enum power_supply_property psp,
+ const union power_supply_propval *val)
+{
+ struct port_data *port = power_supply_get_drvdata(psy);
+ struct charger_data *charger = port->charger;
+ struct device *dev = charger->dev;
+ u16 intval;
+ int ret;
+
+ /* U16_MAX in mV/mA is the maximum supported value */
+ if (val->intval >= U16_MAX * 1000)
+ return -EINVAL;
+ /* A negative number is used to clear the limit */
+ if (val->intval < 0)
+ intval = EC_POWER_LIMIT_NONE;
+ else /* Convert from uA/uV to mA/mV */
+ intval = val->intval / 1000;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ ret = cros_usbpd_charger_set_ext_power_limit(charger, intval,
+ input_voltage_limit);
+ if (ret < 0)
+ break;
+
+ input_current_limit = intval;
+ if (input_current_limit == EC_POWER_LIMIT_NONE)
+ dev_info(dev,
+ "External Current Limit cleared for all ports\n");
+ else
+ dev_info(dev,
+ "External Current Limit set to %dmA for all ports\n",
+ input_current_limit);
+ break;
+ case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+ ret = cros_usbpd_charger_set_ext_power_limit(charger,
+ input_current_limit,
+ intval);
+ if (ret < 0)
+ break;
+
+ input_voltage_limit = intval;
+ if (input_voltage_limit == EC_POWER_LIMIT_NONE)
+ dev_info(dev,
+ "External Voltage Limit cleared for all ports\n");
+ else
+ dev_info(dev,
+ "External Voltage Limit set to %dmV for all ports\n",
+ input_voltage_limit);
+ break;
+ default:
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static int cros_usbpd_charger_property_is_writeable(struct power_supply *psy,
+ enum power_supply_property psp)
+{
+ int ret;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+ case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+ ret = 1;
+ break;
+ default:
+ ret = 0;
+ }
+
+ return ret;
+}
+
static int cros_usbpd_charger_ec_event(struct notifier_block *nb,
unsigned long queued_during_suspend,
void *_notify)
@@ -525,6 +638,9 @@ static int cros_usbpd_charger_probe(struct platform_device *pd)
psy_desc = &port->psy_desc;
psy_desc->get_property = cros_usbpd_charger_get_prop;
+ psy_desc->set_property = cros_usbpd_charger_set_prop;
+ psy_desc->property_is_writeable =
+ cros_usbpd_charger_property_is_writeable;
psy_desc->external_power_changed =
cros_usbpd_charger_power_changed;
psy_cfg.drv_data = port;
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v4 1/2] power: supply: add input power and voltage limit properties
2019-05-07 9:52 [PATCH v4 1/2] power: supply: add input power and voltage limit properties Enric Balletbo i Serra
2019-05-07 9:52 ` Enric Balletbo i Serra
2019-05-07 9:52 ` [PATCH v4 2/2] power: supply: cros: allow to set input voltage and current limit Enric Balletbo i Serra
@ 2019-05-23 19:54 ` Benson Leung
2019-06-25 10:04 ` Enric Balletbo Serra
2 siblings, 1 reply; 7+ messages in thread
From: Benson Leung @ 2019-05-23 19:54 UTC (permalink / raw)
To: Enric Balletbo i Serra
Cc: linux-pm, sre, Sameer Nanda, bleung, rjw, gwendal, linux-kernel,
Len Brown, groeck, Adam.Thomson.Opensource, kernel, Pavel Machek
[-- Attachment #1: Type: text/plain, Size: 7352 bytes --]
Hi Enric,
On Tue, May 07, 2019 at 11:52:47AM +0200, Enric Balletbo i Serra wrote:
> 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>
> ---
>
> Changes in v4:
> - Add also input_power_limit.
>
> Changes in v3:
> - Improve commit log and documentation with Benson comments.
>
> Changes in v2:
> - Document the new property in ABI/testing/sysfs-class-power.
> - Add the Reviewed-by Guenter Roeck tag.
>
> Documentation/ABI/testing/sysfs-class-power | 32 +++++++++++++++++++++
> Documentation/power/power_supply_class.txt | 4 +++
> drivers/power/supply/power_supply_sysfs.c | 2 ++
> include/linux/power_supply.h | 2 ++
> 4 files changed, 40 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> index 5e23e22dce1b..962a27a1daf8 100644
> --- a/Documentation/ABI/testing/sysfs-class-power
> +++ b/Documentation/ABI/testing/sysfs-class-power
> @@ -331,10 +331,42 @@ Description:
> supply. Normally this is configured based on the type of
> connection made (e.g. A configured SDP should output a maximum
> of 500mA so the input current limit is set to the same value).
> + Use preferably input_power_limit, and for problems that can be
> + solved using power limit use input_current_limit.
>
> Access: Read, Write
> Valid values: Represented in microamps
>
> +What: /sys/class/power_supply/<supply_name>/input_voltage_limit
> +Date: May 2019
> +Contact: linux-pm@vger.kernel.org
> +Description:
> + This entry configures the incoming VBUS voltage limit currently
> + set in the supply. Normally this is configured based on
> + system-level knowledge or user input (e.g. This is part of the
> + Pixel C's thermal management strategy to effectively limit the
> + input power to 5V when the screen is on to meet Google's skin
> + temperature targets). Note that this feature should not be
> + used for safety critical things.
> + Use preferably input_power_limit, and for problems that can be
> + solved using power limit use input_voltage_limit.
> +
> + Access: Read, Write
> + Valid values: Represented in microvolts
> +
> +What: /sys/class/power_supply/<supply_name>/input_power_limit
> +Date: May 2019
> +Contact: linux-pm@vger.kernel.org
> +Description:
> + This entry configures the incoming power limit currently set
> + in the supply. Normally this is configured based on
> + system-level knowledge or user input. Use preferably this
> + feature to limit the incoming power and use current/voltage
> + limit only for problems that can be solved using power limit.
> +
> + Access: Read, Write
> + Valid values: Represented in microwatts
> +
> What: /sys/class/power_supply/<supply_name>/online,
> Date: May 2007
> Contact: linux-pm@vger.kernel.org
> diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt
> index 300d37896e51..1e3c705111db 100644
> --- a/Documentation/power/power_supply_class.txt
> +++ b/Documentation/power/power_supply_class.txt
> @@ -137,6 +137,10 @@ power supply object.
>
> INPUT_CURRENT_LIMIT - input current limit programmed by charger. Indicates
> the current drawn from a charging source.
> +INPUT_VOLTAGE_LIMIT - input voltage limit programmed by charger. Indicates
> +the voltage limit from a charging source.
> +INPUT_POWER_LIMIT - input power limit programmed by charger. Indicates
> +the power limit from a charging source.
>
> CHARGE_CONTROL_LIMIT - current charge control limit setting
> CHARGE_CONTROL_LIMIT_MAX - maximum charge control limit setting
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index 5358a80d854f..860db617d241 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -275,6 +275,8 @@ static struct device_attribute power_supply_attrs[] = {
> POWER_SUPPLY_ATTR(charge_control_limit),
> POWER_SUPPLY_ATTR(charge_control_limit_max),
> POWER_SUPPLY_ATTR(input_current_limit),
> + POWER_SUPPLY_ATTR(input_voltage_limit),
> + POWER_SUPPLY_ATTR(input_power_limit),
> POWER_SUPPLY_ATTR(energy_full_design),
> POWER_SUPPLY_ATTR(energy_empty_design),
> POWER_SUPPLY_ATTR(energy_full),
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index 2f9c201a54d1..ba135a5d8996 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -122,6 +122,8 @@ enum power_supply_property {
> POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT,
> POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX,
> POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
> + POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT,
> + POWER_SUPPLY_PROP_INPUT_POWER_LIMIT,
> POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
> POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN,
> POWER_SUPPLY_PROP_ENERGY_FULL,
> --
> 2.20.1
>
--
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@google.com
Chromium OS Project
bleung@chromium.org
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v4 1/2] power: supply: add input power and voltage limit properties
2019-05-23 19:54 ` [PATCH v4 1/2] power: supply: add input power and voltage limit properties Benson Leung
@ 2019-06-25 10:04 ` Enric Balletbo Serra
2019-06-27 18:37 ` Sebastian Reichel
0 siblings, 1 reply; 7+ messages in thread
From: Enric Balletbo Serra @ 2019-06-25 10:04 UTC (permalink / raw)
To: Benson Leung
Cc: Enric Balletbo i Serra, Linux PM list, Sebastian Reichel,
Sameer Nanda, Benson Leung, Rafael J. Wysocki, Gwendal Grignou,
linux-kernel, Len Brown, Guenter Roeck, Adam.Thomson.Opensource,
Collabora Kernel ML, Pavel Machek
Hi Sebastian, Pavel,
Missatge de Benson Leung <bleung@google.com> del dia dj., 23 de maig
2019 a les 21:55:
>
> Hi Enric,
>
> On Tue, May 07, 2019 at 11:52:47AM +0200, Enric Balletbo i Serra wrote:
> > 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>
>
We're close to the merge window so I'm wondering if there are more
concerns on this patchset?
Thanks,
~ Enric
> > ---
> >
> > Changes in v4:
> > - Add also input_power_limit.
> >
> > Changes in v3:
> > - Improve commit log and documentation with Benson comments.
> >
> > Changes in v2:
> > - Document the new property in ABI/testing/sysfs-class-power.
> > - Add the Reviewed-by Guenter Roeck tag.
> >
> > Documentation/ABI/testing/sysfs-class-power | 32 +++++++++++++++++++++
> > Documentation/power/power_supply_class.txt | 4 +++
> > drivers/power/supply/power_supply_sysfs.c | 2 ++
> > include/linux/power_supply.h | 2 ++
> > 4 files changed, 40 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> > index 5e23e22dce1b..962a27a1daf8 100644
> > --- a/Documentation/ABI/testing/sysfs-class-power
> > +++ b/Documentation/ABI/testing/sysfs-class-power
> > @@ -331,10 +331,42 @@ Description:
> > supply. Normally this is configured based on the type of
> > connection made (e.g. A configured SDP should output a maximum
> > of 500mA so the input current limit is set to the same value).
> > + Use preferably input_power_limit, and for problems that can be
> > + solved using power limit use input_current_limit.
> >
> > Access: Read, Write
> > Valid values: Represented in microamps
> >
> > +What: /sys/class/power_supply/<supply_name>/input_voltage_limit
> > +Date: May 2019
> > +Contact: linux-pm@vger.kernel.org
> > +Description:
> > + This entry configures the incoming VBUS voltage limit currently
> > + set in the supply. Normally this is configured based on
> > + system-level knowledge or user input (e.g. This is part of the
> > + Pixel C's thermal management strategy to effectively limit the
> > + input power to 5V when the screen is on to meet Google's skin
> > + temperature targets). Note that this feature should not be
> > + used for safety critical things.
> > + Use preferably input_power_limit, and for problems that can be
> > + solved using power limit use input_voltage_limit.
> > +
> > + Access: Read, Write
> > + Valid values: Represented in microvolts
> > +
> > +What: /sys/class/power_supply/<supply_name>/input_power_limit
> > +Date: May 2019
> > +Contact: linux-pm@vger.kernel.org
> > +Description:
> > + This entry configures the incoming power limit currently set
> > + in the supply. Normally this is configured based on
> > + system-level knowledge or user input. Use preferably this
> > + feature to limit the incoming power and use current/voltage
> > + limit only for problems that can be solved using power limit.
> > +
> > + Access: Read, Write
> > + Valid values: Represented in microwatts
> > +
> > What: /sys/class/power_supply/<supply_name>/online,
> > Date: May 2007
> > Contact: linux-pm@vger.kernel.org
> > diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt
> > index 300d37896e51..1e3c705111db 100644
> > --- a/Documentation/power/power_supply_class.txt
> > +++ b/Documentation/power/power_supply_class.txt
> > @@ -137,6 +137,10 @@ power supply object.
> >
> > INPUT_CURRENT_LIMIT - input current limit programmed by charger. Indicates
> > the current drawn from a charging source.
> > +INPUT_VOLTAGE_LIMIT - input voltage limit programmed by charger. Indicates
> > +the voltage limit from a charging source.
> > +INPUT_POWER_LIMIT - input power limit programmed by charger. Indicates
> > +the power limit from a charging source.
> >
> > CHARGE_CONTROL_LIMIT - current charge control limit setting
> > CHARGE_CONTROL_LIMIT_MAX - maximum charge control limit setting
> > diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> > index 5358a80d854f..860db617d241 100644
> > --- a/drivers/power/supply/power_supply_sysfs.c
> > +++ b/drivers/power/supply/power_supply_sysfs.c
> > @@ -275,6 +275,8 @@ static struct device_attribute power_supply_attrs[] = {
> > POWER_SUPPLY_ATTR(charge_control_limit),
> > POWER_SUPPLY_ATTR(charge_control_limit_max),
> > POWER_SUPPLY_ATTR(input_current_limit),
> > + POWER_SUPPLY_ATTR(input_voltage_limit),
> > + POWER_SUPPLY_ATTR(input_power_limit),
> > POWER_SUPPLY_ATTR(energy_full_design),
> > POWER_SUPPLY_ATTR(energy_empty_design),
> > POWER_SUPPLY_ATTR(energy_full),
> > diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> > index 2f9c201a54d1..ba135a5d8996 100644
> > --- a/include/linux/power_supply.h
> > +++ b/include/linux/power_supply.h
> > @@ -122,6 +122,8 @@ enum power_supply_property {
> > POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT,
> > POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX,
> > POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
> > + POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT,
> > + POWER_SUPPLY_PROP_INPUT_POWER_LIMIT,
> > POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
> > POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN,
> > POWER_SUPPLY_PROP_ENERGY_FULL,
> > --
> > 2.20.1
> >
>
> --
> Benson Leung
> Staff Software Engineer
> Chrome OS Kernel
> Google Inc.
> bleung@google.com
> Chromium OS Project
> bleung@chromium.org
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v4 1/2] power: supply: add input power and voltage limit properties
2019-06-25 10:04 ` Enric Balletbo Serra
@ 2019-06-27 18:37 ` Sebastian Reichel
0 siblings, 0 replies; 7+ messages in thread
From: Sebastian Reichel @ 2019-06-27 18:37 UTC (permalink / raw)
To: Enric Balletbo Serra
Cc: Benson Leung, Enric Balletbo i Serra, Linux PM list,
Sameer Nanda, Benson Leung, Rafael J. Wysocki, Gwendal Grignou,
linux-kernel, Len Brown, Guenter Roeck, Adam.Thomson.Opensource,
Collabora Kernel ML, Pavel Machek
[-- Attachment #1: Type: text/plain, Size: 8857 bytes --]
Hi,
I just queued both patches. Thanks for the detailed description and
documentation.
-- Sebastian
On Tue, Jun 25, 2019 at 12:04:13PM +0200, Enric Balletbo Serra wrote:
> Hi Sebastian, Pavel,
>
> Missatge de Benson Leung <bleung@google.com> del dia dj., 23 de maig
> 2019 a les 21:55:
> >
> > Hi Enric,
> >
> > On Tue, May 07, 2019 at 11:52:47AM +0200, Enric Balletbo i Serra wrote:
> > > 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>
> >
>
> We're close to the merge window so I'm wondering if there are more
> concerns on this patchset?
>
> Thanks,
> ~ Enric
>
> > > ---
> > >
> > > Changes in v4:
> > > - Add also input_power_limit.
> > >
> > > Changes in v3:
> > > - Improve commit log and documentation with Benson comments.
> > >
> > > Changes in v2:
> > > - Document the new property in ABI/testing/sysfs-class-power.
> > > - Add the Reviewed-by Guenter Roeck tag.
> > >
> > > Documentation/ABI/testing/sysfs-class-power | 32 +++++++++++++++++++++
> > > Documentation/power/power_supply_class.txt | 4 +++
> > > drivers/power/supply/power_supply_sysfs.c | 2 ++
> > > include/linux/power_supply.h | 2 ++
> > > 4 files changed, 40 insertions(+)
> > >
> > > diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> > > index 5e23e22dce1b..962a27a1daf8 100644
> > > --- a/Documentation/ABI/testing/sysfs-class-power
> > > +++ b/Documentation/ABI/testing/sysfs-class-power
> > > @@ -331,10 +331,42 @@ Description:
> > > supply. Normally this is configured based on the type of
> > > connection made (e.g. A configured SDP should output a maximum
> > > of 500mA so the input current limit is set to the same value).
> > > + Use preferably input_power_limit, and for problems that can be
> > > + solved using power limit use input_current_limit.
> > >
> > > Access: Read, Write
> > > Valid values: Represented in microamps
> > >
> > > +What: /sys/class/power_supply/<supply_name>/input_voltage_limit
> > > +Date: May 2019
> > > +Contact: linux-pm@vger.kernel.org
> > > +Description:
> > > + This entry configures the incoming VBUS voltage limit currently
> > > + set in the supply. Normally this is configured based on
> > > + system-level knowledge or user input (e.g. This is part of the
> > > + Pixel C's thermal management strategy to effectively limit the
> > > + input power to 5V when the screen is on to meet Google's skin
> > > + temperature targets). Note that this feature should not be
> > > + used for safety critical things.
> > > + Use preferably input_power_limit, and for problems that can be
> > > + solved using power limit use input_voltage_limit.
> > > +
> > > + Access: Read, Write
> > > + Valid values: Represented in microvolts
> > > +
> > > +What: /sys/class/power_supply/<supply_name>/input_power_limit
> > > +Date: May 2019
> > > +Contact: linux-pm@vger.kernel.org
> > > +Description:
> > > + This entry configures the incoming power limit currently set
> > > + in the supply. Normally this is configured based on
> > > + system-level knowledge or user input. Use preferably this
> > > + feature to limit the incoming power and use current/voltage
> > > + limit only for problems that can be solved using power limit.
> > > +
> > > + Access: Read, Write
> > > + Valid values: Represented in microwatts
> > > +
> > > What: /sys/class/power_supply/<supply_name>/online,
> > > Date: May 2007
> > > Contact: linux-pm@vger.kernel.org
> > > diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt
> > > index 300d37896e51..1e3c705111db 100644
> > > --- a/Documentation/power/power_supply_class.txt
> > > +++ b/Documentation/power/power_supply_class.txt
> > > @@ -137,6 +137,10 @@ power supply object.
> > >
> > > INPUT_CURRENT_LIMIT - input current limit programmed by charger. Indicates
> > > the current drawn from a charging source.
> > > +INPUT_VOLTAGE_LIMIT - input voltage limit programmed by charger. Indicates
> > > +the voltage limit from a charging source.
> > > +INPUT_POWER_LIMIT - input power limit programmed by charger. Indicates
> > > +the power limit from a charging source.
> > >
> > > CHARGE_CONTROL_LIMIT - current charge control limit setting
> > > CHARGE_CONTROL_LIMIT_MAX - maximum charge control limit setting
> > > diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> > > index 5358a80d854f..860db617d241 100644
> > > --- a/drivers/power/supply/power_supply_sysfs.c
> > > +++ b/drivers/power/supply/power_supply_sysfs.c
> > > @@ -275,6 +275,8 @@ static struct device_attribute power_supply_attrs[] = {
> > > POWER_SUPPLY_ATTR(charge_control_limit),
> > > POWER_SUPPLY_ATTR(charge_control_limit_max),
> > > POWER_SUPPLY_ATTR(input_current_limit),
> > > + POWER_SUPPLY_ATTR(input_voltage_limit),
> > > + POWER_SUPPLY_ATTR(input_power_limit),
> > > POWER_SUPPLY_ATTR(energy_full_design),
> > > POWER_SUPPLY_ATTR(energy_empty_design),
> > > POWER_SUPPLY_ATTR(energy_full),
> > > diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> > > index 2f9c201a54d1..ba135a5d8996 100644
> > > --- a/include/linux/power_supply.h
> > > +++ b/include/linux/power_supply.h
> > > @@ -122,6 +122,8 @@ enum power_supply_property {
> > > POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT,
> > > POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX,
> > > POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
> > > + POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT,
> > > + POWER_SUPPLY_PROP_INPUT_POWER_LIMIT,
> > > POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
> > > POWER_SUPPLY_PROP_ENERGY_EMPTY_DESIGN,
> > > POWER_SUPPLY_PROP_ENERGY_FULL,
> > > --
> > > 2.20.1
> > >
> >
> > --
> > Benson Leung
> > Staff Software Engineer
> > Chrome OS Kernel
> > Google Inc.
> > bleung@google.com
> > Chromium OS Project
> > bleung@chromium.org
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^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2019-06-27 18:37 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-07 9:52 [PATCH v4 1/2] power: supply: add input power and voltage limit properties Enric Balletbo i Serra
2019-05-07 9:52 ` Enric Balletbo i Serra
2019-05-07 9:52 ` [PATCH v4 2/2] power: supply: cros: allow to set input voltage and current limit Enric Balletbo i Serra
2019-05-07 9:52 ` Enric Balletbo i Serra
2019-05-23 19:54 ` [PATCH v4 1/2] power: supply: add input power and voltage limit properties Benson Leung
2019-06-25 10:04 ` Enric Balletbo Serra
2019-06-27 18:37 ` Sebastian Reichel
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