[PATCH] HID: i2c-hid: Remove runtime power management

[Kai-Heng Feng <kai.heng.feng@canonical.com>]

Runtime power management in i2c-hid brings lots of issues, such as:
- When transitioning from display manager to desktop session, i2c-hid
was closed and opened, so the device was set to SLEEP and ON in a short
period. Vendors confirmed that their devices can't handle fast ON/SLEEP
command because Windows doesn't have this behavior.

- When rebooting, i2c-hid was closed, and the driver core put the device
back to full power before shutdown. This behavior also triggers a quick
SLEEP and ON commands that some devices can't handle, renders an
unusable touchpad after reboot.

- Runtime power management is only useful when i2c-hid isn't opened,
i.e. a laptop without desktop session, which isn't that common.

- Most importantly, my power meter reports little to none energy saving
when i2c-hid is runtime suspended.

So let's remove runtime power management since there is no actual
benefit.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/hid/i2c-hid/i2c-hid-core.c | 111 ++---------------------------
 1 file changed, 4 insertions(+), 107 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 2a7c6e33bb1c..5ab4982b3a7b 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -26,7 +26,6 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/pm.h>
-#include <linux/pm_runtime.h>
 #include <linux/device.h>
 #include <linux/wait.h>
 #include <linux/err.h>
@@ -48,8 +47,6 @@
 /* quirks to control the device */
 #define I2C_HID_QUIRK_SET_PWR_WAKEUP_DEV	BIT(0)
 #define I2C_HID_QUIRK_NO_IRQ_AFTER_RESET	BIT(1)
-#define I2C_HID_QUIRK_NO_RUNTIME_PM		BIT(2)
-#define I2C_HID_QUIRK_DELAY_AFTER_SLEEP		BIT(3)
 #define I2C_HID_QUIRK_BOGUS_IRQ			BIT(4)
 
 /* flags */
@@ -172,14 +169,7 @@ static const struct i2c_hid_quirks {
 	{ USB_VENDOR_ID_WEIDA, HID_ANY_ID,
 		I2C_HID_QUIRK_SET_PWR_WAKEUP_DEV },
 	{ I2C_VENDOR_ID_HANTICK, I2C_PRODUCT_ID_HANTICK_5288,
-		I2C_HID_QUIRK_NO_IRQ_AFTER_RESET |
-		I2C_HID_QUIRK_NO_RUNTIME_PM },
-	{ I2C_VENDOR_ID_RAYDIUM, I2C_PRODUCT_ID_RAYDIUM_4B33,
-		I2C_HID_QUIRK_DELAY_AFTER_SLEEP },
-	{ USB_VENDOR_ID_LG, I2C_DEVICE_ID_LG_8001,
-		I2C_HID_QUIRK_NO_RUNTIME_PM },
-	{ I2C_VENDOR_ID_GOODIX, I2C_DEVICE_ID_GOODIX_01F0,
-		I2C_HID_QUIRK_NO_RUNTIME_PM },
+		I2C_HID_QUIRK_NO_IRQ_AFTER_RESET },
 	{ USB_VENDOR_ID_ELAN, HID_ANY_ID,
 		 I2C_HID_QUIRK_BOGUS_IRQ },
 	{ 0, 0 }
@@ -397,7 +387,6 @@ static int i2c_hid_set_power(struct i2c_client *client, int power_state)
 {
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
 	int ret;
-	unsigned long now, delay;
 
 	i2c_hid_dbg(ihid, "%s\n", __func__);
 
@@ -415,22 +404,9 @@ static int i2c_hid_set_power(struct i2c_client *client, int power_state)
 			goto set_pwr_exit;
 	}
 
-	if (ihid->quirks & I2C_HID_QUIRK_DELAY_AFTER_SLEEP &&
-	    power_state == I2C_HID_PWR_ON) {
-		now = jiffies;
-		if (time_after(ihid->sleep_delay, now)) {
-			delay = jiffies_to_usecs(ihid->sleep_delay - now);
-			usleep_range(delay, delay + 1);
-		}
-	}
-
 	ret = __i2c_hid_command(client, &hid_set_power_cmd, power_state,
 		0, NULL, 0, NULL, 0);
 
-	if (ihid->quirks & I2C_HID_QUIRK_DELAY_AFTER_SLEEP &&
-	    power_state == I2C_HID_PWR_SLEEP)
-		ihid->sleep_delay = jiffies + msecs_to_jiffies(20);
-
 	if (ret)
 		dev_err(&client->dev, "failed to change power setting.\n");
 
@@ -791,11 +767,6 @@ static int i2c_hid_open(struct hid_device *hid)
 {
 	struct i2c_client *client = hid->driver_data;
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
-	int ret = 0;
-
-	ret = pm_runtime_get_sync(&client->dev);
-	if (ret < 0)
-		return ret;
 
 	set_bit(I2C_HID_STARTED, &ihid->flags);
 	return 0;
@@ -807,27 +778,6 @@ static void i2c_hid_close(struct hid_device *hid)
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
 
 	clear_bit(I2C_HID_STARTED, &ihid->flags);
-
-	/* Save some power */
-	pm_runtime_put(&client->dev);
-}
-
-static int i2c_hid_power(struct hid_device *hid, int lvl)
-{
-	struct i2c_client *client = hid->driver_data;
-	struct i2c_hid *ihid = i2c_get_clientdata(client);
-
-	i2c_hid_dbg(ihid, "%s lvl:%d\n", __func__, lvl);
-
-	switch (lvl) {
-	case PM_HINT_FULLON:
-		pm_runtime_get_sync(&client->dev);
-		break;
-	case PM_HINT_NORMAL:
-		pm_runtime_put(&client->dev);
-		break;
-	}
-	return 0;
 }
 
 struct hid_ll_driver i2c_hid_ll_driver = {
@@ -836,7 +786,6 @@ struct hid_ll_driver i2c_hid_ll_driver = {
 	.stop = i2c_hid_stop,
 	.open = i2c_hid_open,
 	.close = i2c_hid_close,
-	.power = i2c_hid_power,
 	.output_report = i2c_hid_output_report,
 	.raw_request = i2c_hid_raw_request,
 };
@@ -1104,9 +1053,6 @@ static int i2c_hid_probe(struct i2c_client *client,
 
 	i2c_hid_acpi_fix_up_power(&client->dev);
 
-	pm_runtime_get_noresume(&client->dev);
-	pm_runtime_set_active(&client->dev);
-	pm_runtime_enable(&client->dev);
 	device_enable_async_suspend(&client->dev);
 
 	/* Make sure there is something at this address */
@@ -1154,9 +1100,6 @@ static int i2c_hid_probe(struct i2c_client *client,
 		goto err_mem_free;
 	}
 
-	if (!(ihid->quirks & I2C_HID_QUIRK_NO_RUNTIME_PM))
-		pm_runtime_put(&client->dev);
-
 	return 0;
 
 err_mem_free:
@@ -1166,9 +1109,6 @@ static int i2c_hid_probe(struct i2c_client *client,
 	free_irq(client->irq, ihid);
 
 err_pm:
-	pm_runtime_put_noidle(&client->dev);
-	pm_runtime_disable(&client->dev);
-
 err_regulator:
 	regulator_bulk_disable(ARRAY_SIZE(ihid->pdata.supplies),
 			       ihid->pdata.supplies);
@@ -1181,12 +1121,6 @@ static int i2c_hid_remove(struct i2c_client *client)
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
 	struct hid_device *hid;
 
-	if (!(ihid->quirks & I2C_HID_QUIRK_NO_RUNTIME_PM))
-		pm_runtime_get_sync(&client->dev);
-	pm_runtime_disable(&client->dev);
-	pm_runtime_set_suspended(&client->dev);
-	pm_runtime_put_noidle(&client->dev);
-
 	hid = ihid->hid;
 	hid_destroy_device(hid);
 
@@ -1219,25 +1153,15 @@ static int i2c_hid_suspend(struct device *dev)
 	int wake_status;
 
 	if (hid->driver && hid->driver->suspend) {
-		/*
-		 * Wake up the device so that IO issues in
-		 * HID driver's suspend code can succeed.
-		 */
-		ret = pm_runtime_resume(dev);
-		if (ret < 0)
-			return ret;
-
 		ret = hid->driver->suspend(hid, PMSG_SUSPEND);
 		if (ret < 0)
 			return ret;
 	}
 
-	if (!pm_runtime_suspended(dev)) {
-		/* Save some power */
-		i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
+	/* Save some power */
+	i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
 
-		disable_irq(client->irq);
-	}
+	disable_irq(client->irq);
 
 	if (device_may_wakeup(&client->dev)) {
 		wake_status = enable_irq_wake(client->irq);
@@ -1279,11 +1203,6 @@ static int i2c_hid_resume(struct device *dev)
 				wake_status);
 	}
 
-	/* We'll resume to full power */
-	pm_runtime_disable(dev);
-	pm_runtime_set_active(dev);
-	pm_runtime_enable(dev);
-
 	enable_irq(client->irq);
 
 	/* Instead of resetting device, simply powers the device on. This
@@ -1304,30 +1223,8 @@ static int i2c_hid_resume(struct device *dev)
 }
 #endif
 
-#ifdef CONFIG_PM
-static int i2c_hid_runtime_suspend(struct device *dev)
-{
-	struct i2c_client *client = to_i2c_client(dev);
-
-	i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
-	disable_irq(client->irq);
-	return 0;
-}
-
-static int i2c_hid_runtime_resume(struct device *dev)
-{
-	struct i2c_client *client = to_i2c_client(dev);
-
-	enable_irq(client->irq);
-	i2c_hid_set_power(client, I2C_HID_PWR_ON);
-	return 0;
-}
-#endif
-
 static const struct dev_pm_ops i2c_hid_pm = {
 	SET_SYSTEM_SLEEP_PM_OPS(i2c_hid_suspend, i2c_hid_resume)
-	SET_RUNTIME_PM_OPS(i2c_hid_runtime_suspend, i2c_hid_runtime_resume,
-			   NULL)
 };
 
 static const struct i2c_device_id i2c_hid_id_table[] = {
-- 
2.17.1