[PATCH v4 2/2] input: touchscreen: goodix: Hold controller in reset during suspend

[Jan Jasper de Kroon <jajadekroon@gmail.com>]

From: Ondřej Jirman <megi@xff.cz>

The Goodix touchscreen controller used in PinePhone is not properly
suspended during system sleep, leading to high power consumption. This
commit modifies the driver to hold the controller in reset during
system sleep, reducing power consumption by around 40mW.

The original patch also disabled the regulators during system sleep, but
this could cause issues with other peripherals attached to the same power
supplies. Hence, this commit only holds the controller in reset during
system sleep and does not attempt to power it off.

A separate commit adds a new device tree property "goodix-hold-in-reset"
to control the hold-in-reset behavior of the controller during system sleep.

Signed-off-by: Ondrej Jirman <megi@xff.cz>
Signed-off-by: Jan Jasper de Kroon <jajadekroon@gmail.com>
---
Changes from v3 to v4:
- Renamed the hold-in-reset-in-suspend function to 
  goodix-hold-in-reset to prevent potential naming conflicts with other 
  functions in the codebase. No functional changes were made.

Changes from v2 to v3:
- Some patch style cleaning up, to confirm to submission standard.

Changes from v1 to v2:
- Rewrote the commit message and function name to better reflect it's 
  behavior.
 drivers/input/touchscreen/goodix.c | 23 +++++++++++++++++++++++
 drivers/input/touchscreen/goodix.h |  1 +
 2 files changed, 24 insertions(+)

diff --git a/drivers/input/touchscreen/goodix.c b/drivers/input/touchscreen/goodix.c
index b348172f19c3..9f86bdfbfc73 100644
--- a/drivers/input/touchscreen/goodix.c
+++ b/drivers/input/touchscreen/goodix.c
@@ -1284,6 +1284,7 @@ static void goodix_disable_regulators(void *arg)
 
 static int goodix_ts_probe(struct i2c_client *client)
 {
+	struct device_node *np = client->dev.of_node;
 	struct goodix_ts_data *ts;
 	const char *cfg_name;
 	int error;
@@ -1303,6 +1304,7 @@ static int goodix_ts_probe(struct i2c_client *client)
 	i2c_set_clientdata(client, ts);
 	init_completion(&ts->firmware_loading_complete);
 	ts->contact_size = GOODIX_CONTACT_SIZE;
+	ts->goodix_hold_in_reset = of_property_read_bool(np, "goodix-hold-in-reset");
 
 	error = goodix_get_gpio_config(ts);
 	if (error)
@@ -1410,6 +1412,13 @@ static int goodix_suspend(struct device *dev)
 	if (ts->load_cfg_from_disk)
 		wait_for_completion(&ts->firmware_loading_complete);
 
+	if (ts->goodix_hold_in_reset) {
+		goodix_free_irq(ts);
+		goodix_irq_direction_output(ts, 0);
+		gpiod_direction_output(ts->gpiod_rst, 0);
+		return 0;
+	}
+
 	/* We need gpio pins to suspend/resume */
 	if (ts->irq_pin_access_method == IRQ_PIN_ACCESS_NONE) {
 		disable_irq(client->irq);
@@ -1455,6 +1464,20 @@ static int goodix_resume(struct device *dev)
 	u8 config_ver;
 	int error;
 
+	if (ts->goodix_hold_in_reset) {
+		error = goodix_reset(ts);
+		if (error) {
+			dev_err(dev, "Controller reset failed.\n");
+			return error;
+		}
+
+		error = goodix_request_irq(ts);
+		if (error)
+			return error;
+
+		return 0;
+	}
+
 	if (ts->irq_pin_access_method == IRQ_PIN_ACCESS_NONE) {
 		enable_irq(client->irq);
 		return 0;
diff --git a/drivers/input/touchscreen/goodix.h b/drivers/input/touchscreen/goodix.h
index 87797cc88b32..7be7eb1a8f27 100644
--- a/drivers/input/touchscreen/goodix.h
+++ b/drivers/input/touchscreen/goodix.h
@@ -104,6 +104,7 @@ struct goodix_ts_data {
 	u8 main_clk[GOODIX_MAIN_CLK_LEN];
 	int bak_ref_len;
 	u8 *bak_ref;
+	bool goodix_hold_in_reset;
 };
 
 int goodix_i2c_read(struct i2c_client *client, u16 reg, u8 *buf, int len);
-- 
2.34.3