[PATCH v2 0/2] Add a property to turn off the max touch controller in suspend mode

[PATCH v2 0/2] Add a property to turn off the max touch controller in suspend mode

[Stefan Eichenberger]

From: Stefan Eichenberger <stefan.eichenberger@toradex.com>

Our hardware has a shared regulator that powers various peripherals such
as the display, touch, USB hub, etc. Since the Maxtouch controller
doesn't currently allow it to be turned off, this regulator has to stay
on in suspend mode. This increases the overall power consumption. In
order to turn off the controller when the system goes into suspend mode,
this series adds a device tree property to the maxtouch driver that
allows the controller to be turned off completely and ensurs that it can
resume from the power off state.

Changes since v1:
- Rename the property and change the description (Krzysztof, Linus,
  Dmitry, Conor)

Stefan Eichenberger (2):
  dt-bindings: input: atmel,maxtouch: add poweroff-sleep property
  Input: atmel_mxt_ts - support poweroff in suspend

 .../bindings/input/atmel,maxtouch.yaml        |  6 ++
 drivers/input/touchscreen/atmel_mxt_ts.c      | 72 ++++++++++++++-----
 2 files changed, 61 insertions(+), 17 deletions(-)

-- 
2.40.1

[PATCH v2 1/2] dt-bindings: input: atmel,maxtouch: add poweroff-sleep property

[Stefan Eichenberger]

From: Stefan Eichenberger <stefan.eichenberger@toradex.com>

Add a new property to indicate that the device should power off rather
than use deep sleep. Deep sleep is a feature of the controller that
expects the controller to remain powered in suspend. However, if a
display shares its regulator with the touch controller, we may want to
do a power off so that the display and touch controller do not use any
power.

Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
---
 Documentation/devicetree/bindings/input/atmel,maxtouch.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/atmel,maxtouch.yaml b/Documentation/devicetree/bindings/input/atmel,maxtouch.yaml
index c40799355ed7..8de5f539b30e 100644
--- a/Documentation/devicetree/bindings/input/atmel,maxtouch.yaml
+++ b/Documentation/devicetree/bindings/input/atmel,maxtouch.yaml
@@ -87,6 +87,12 @@ properties:
       - 2 # ATMEL_MXT_WAKEUP_GPIO
     default: 0
 
+  atmel,poweroff-sleep:
+    description: |
+      Instead of using the deep sleep feature of the maXTouch controller,
+      poweroff the regulators.
+    type: boolean
+
   wakeup-source:
     type: boolean
 
-- 
2.40.1

[PATCH v2 2/2] Input: atmel_mxt_ts - support poweroff in suspend

[Stefan Eichenberger]

From: Stefan Eichenberger <stefan.eichenberger@toradex.com>

Add a new device tree property to indicate that the device should be
powered off in suspend mode. We have a shared regulator that powers the
display, a USB hub and some other peripherals. The maXTouch controller
doesn't normally disable the regulator in suspend mode, so our extra
peripherals stay powered on. This is not desirable as it consumes more
power. With this patch we add the option to disable the regulator in
suspend mode for the maXTouch and accept the longer initialisation time.

Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 72 ++++++++++++++++++------
 1 file changed, 55 insertions(+), 17 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 20094b9899f0..3f7f58f1c930 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -317,6 +317,7 @@ struct mxt_data {
 	struct gpio_desc *reset_gpio;
 	struct gpio_desc *wake_gpio;
 	bool use_retrigen_workaround;
+	bool poweroff_sleep;
 
 	/* Cached parameters from object table */
 	u16 T5_address;
@@ -2799,15 +2800,18 @@ static int mxt_configure_objects(struct mxt_data *data,
 			dev_warn(dev, "Error %d updating config\n", error);
 	}
 
-	if (data->multitouch) {
-		error = mxt_initialize_input_device(data);
-		if (error)
-			return error;
-	} else {
-		dev_warn(dev, "No touch object detected\n");
-	}
+	/* If input device is not already registered */
+	if (!data->input_dev) {
+		if (data->multitouch) {
+			error = mxt_initialize_input_device(data);
+			if (error)
+				return error;
+		} else {
+			dev_warn(dev, "No touch object detected\n");
+		}
 
-	mxt_debug_init(data);
+		mxt_debug_init(data);
+	}
 
 	return 0;
 }
@@ -3328,6 +3332,8 @@ static int mxt_probe(struct i2c_client *client)
 		msleep(MXT_RESET_INVALID_CHG);
 	}
 
+	data->poweroff_sleep = device_property_read_bool(&client->dev,
+							 "atmel,poweroff-sleep");
 	/*
 	 * Controllers like mXT1386 have a dedicated WAKE line that could be
 	 * connected to a GPIO or to I2C SCL pin, or permanently asserted low.
@@ -3390,12 +3396,21 @@ static int mxt_suspend(struct device *dev)
 	if (!input_dev)
 		return 0;
 
-	mutex_lock(&input_dev->mutex);
+	if (!device_may_wakeup(dev) && data->poweroff_sleep) {
+		if (data->reset_gpio)
+			gpiod_set_value(data->reset_gpio, 1);
 
-	if (input_device_enabled(input_dev))
-		mxt_stop(data);
+		regulator_bulk_disable(ARRAY_SIZE(data->regulators),
+				data->regulators);
+		data->T44_address = 0;
+	} else {
+		mutex_lock(&input_dev->mutex);
+
+		if (input_device_enabled(input_dev))
+			mxt_stop(data);
 
-	mutex_unlock(&input_dev->mutex);
+		mutex_unlock(&input_dev->mutex);
+	}
 
 	disable_irq(data->irq);
 
@@ -3411,14 +3426,37 @@ static int mxt_resume(struct device *dev)
 	if (!input_dev)
 		return 0;
 
-	enable_irq(data->irq);
+	if (!device_may_wakeup(dev) && data->poweroff_sleep) {
+		int ret;
 
-	mutex_lock(&input_dev->mutex);
+		ret = regulator_bulk_enable(ARRAY_SIZE(data->regulators),
+				data->regulators);
+		if (ret) {
+			dev_err(dev, "failed to enable regulators: %d\n",
+					ret);
+			return ret;
+		}
+		msleep(MXT_BACKUP_TIME);
 
-	if (input_device_enabled(input_dev))
-		mxt_start(data);
+		if (data->reset_gpio) {
+			/* Wait a while and then de-assert the RESET GPIO line */
+			msleep(MXT_RESET_GPIO_TIME);
+			gpiod_set_value(data->reset_gpio, 0);
+			msleep(MXT_RESET_INVALID_CHG);
+		}
 
-	mutex_unlock(&input_dev->mutex);
+		/* This also enables the irq again */
+		mxt_initialize(data);
+	} else {
+		enable_irq(data->irq);
+
+		mutex_lock(&input_dev->mutex);
+
+		if (input_device_enabled(input_dev))
+			mxt_start(data);
+
+		mutex_unlock(&input_dev->mutex);
+	}
 
 	return 0;
 }
-- 
2.40.1

Re: [PATCH v2 1/2] dt-bindings: input: atmel,maxtouch: add poweroff-sleep property

[Linus Walleij]

On Fri, Dec 22, 2023 at 10:53 AM Stefan Eichenberger <eichest@gmail.com> wrote:

> From: Stefan Eichenberger <stefan.eichenberger@toradex.com>
>
> Add a new property to indicate that the device should power off rather
> than use deep sleep. Deep sleep is a feature of the controller that
> expects the controller to remain powered in suspend. However, if a
> display shares its regulator with the touch controller, we may want to
> do a power off so that the display and touch controller do not use any
> power.
>
> Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>

This LGTM:
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

Re: [PATCH v2 1/2] dt-bindings: input: atmel,maxtouch: add poweroff-sleep property

[Krzysztof Kozlowski]

On 22/12/2023 10:52, Stefan Eichenberger wrote:
> From: Stefan Eichenberger <stefan.eichenberger@toradex.com>
> 
> Add a new property to indicate that the device should power off rather
> than use deep sleep. Deep sleep is a feature of the controller that
> expects the controller to remain powered in suspend. However, if a
> display shares its regulator with the touch controller, we may want to
> do a power off so that the display and touch controller do not use any
> power.
> 

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof