[RFC v2 2/7] HID: i2c-hid: Split i2c_hid_hwreset() in start() and finish() functions

[Hans de Goede <hdegoede@redhat.com>]

Split i2c_hid_hwreset() into:

i2c_hid_start_hwreset() which sends the PWR_ON and reset commands; and
i2c_hid_finish_hwreset() which actually waits for the reset to complete.

This is a preparation patch for removing the need for
I2C_HID_QUIRK_NO_IRQ_AFTER_RESET by making i2c-hid behave
more like Windows.

No functional changes intended.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
-Move the mutex_[un]lock(&ihid->reset_lock) calls from
 i2c_hid_start_hwreset() / i2c_hid_finish_hwreset() to the callers
 to make the locking more clear
---
 drivers/hid/i2c-hid/i2c-hid-core.c | 38 ++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 74dd145275f1..607ed9b7ba1b 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -426,7 +426,7 @@ static int i2c_hid_set_power(struct i2c_hid *ihid, int power_state)
 	return ret;
 }
 
-static int i2c_hid_hwreset(struct i2c_hid *ihid)
+static int i2c_hid_start_hwreset(struct i2c_hid *ihid)
 {
 	size_t length = 0;
 	int ret;
@@ -438,11 +438,11 @@ static int i2c_hid_hwreset(struct i2c_hid *ihid)
 	 * being reset. Otherwise we may lose the reset complete
 	 * interrupt.
 	 */
-	mutex_lock(&ihid->reset_lock);
+	lockdep_assert_held(&ihid->reset_lock);
 
 	ret = i2c_hid_set_power(ihid, I2C_HID_PWR_ON);
 	if (ret)
-		goto err_unlock;
+		return ret;
 
 	/* Prepare reset command. Command register goes first. */
 	*(__le16 *)ihid->cmdbuf = ihid->hdesc.wCommandRegister;
@@ -460,6 +460,18 @@ static int i2c_hid_hwreset(struct i2c_hid *ihid)
 		goto err_clear_reset;
 	}
 
+	return 0;
+
+err_clear_reset:
+	clear_bit(I2C_HID_RESET_PENDING, &ihid->flags);
+	i2c_hid_set_power(ihid, I2C_HID_PWR_SLEEP);
+	return ret;
+}
+
+static int i2c_hid_finish_hwreset(struct i2c_hid *ihid)
+{
+	int ret = 0;
+
 	i2c_hid_dbg(ihid, "%s: waiting...\n", __func__);
 
 	if (ihid->quirks & I2C_HID_QUIRK_NO_IRQ_AFTER_RESET) {
@@ -479,14 +491,11 @@ static int i2c_hid_hwreset(struct i2c_hid *ihid)
 	if (!(ihid->quirks & I2C_HID_QUIRK_NO_WAKEUP_AFTER_RESET))
 		ret = i2c_hid_set_power(ihid, I2C_HID_PWR_ON);
 
-	mutex_unlock(&ihid->reset_lock);
 	return ret;
 
 err_clear_reset:
 	clear_bit(I2C_HID_RESET_PENDING, &ihid->flags);
 	i2c_hid_set_power(ihid, I2C_HID_PWR_SLEEP);
-err_unlock:
-	mutex_unlock(&ihid->reset_lock);
 	return ret;
 }
 
@@ -733,7 +742,11 @@ static int i2c_hid_parse(struct hid_device *hid)
 	}
 
 	do {
-		ret = i2c_hid_hwreset(ihid);
+		mutex_lock(&ihid->reset_lock);
+		ret = i2c_hid_start_hwreset(ihid);
+		if (ret == 0)
+			ret = i2c_hid_finish_hwreset(ihid);
+		mutex_unlock(&ihid->reset_lock);
 		if (ret)
 			msleep(1000);
 	} while (tries-- > 0 && ret);
@@ -976,10 +989,15 @@ static int i2c_hid_core_resume(struct i2c_hid *ihid)
 	 * However some ALPS touchpads generate IRQ storm without reset, so
 	 * let's still reset them here.
 	 */
-	if (ihid->quirks & I2C_HID_QUIRK_RESET_ON_RESUME)
-		ret = i2c_hid_hwreset(ihid);
-	else
+	if (ihid->quirks & I2C_HID_QUIRK_RESET_ON_RESUME) {
+		mutex_lock(&ihid->reset_lock);
+		ret = i2c_hid_start_hwreset(ihid);
+		if (ret == 0)
+			ret = i2c_hid_finish_hwreset(ihid);
+		mutex_unlock(&ihid->reset_lock);
+	} else {
 		ret = i2c_hid_set_power(ihid, I2C_HID_PWR_ON);
+	}
 
 	if (ret)
 		return ret;
-- 
2.41.0