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HID: i2c-hid: Send power-on command after reset
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Before commit 67b18df ("HID: i2c-hid: Remove runtime power
management"), any i2c-hid touchscreens would typically be runtime-suspended
between the driver loading and Xorg or a Wayland compositor opening it,
causing it to be resumed again. This means that before this change,
we would call i2c_hid_set_power(OFF), i2c_hid_set_power(ON) before the
graphical session would start listening to the touchscreen.

It turns out that at least some SIS touchscreens, such as the one found
on the Asus T100HA, need a power-on command after reset, otherwise they
will not send any events.

Fixes: 67b18df ("HID: i2c-hid: Remove runtime power management")
Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Hans de Goede authored and Jiri Kosina committed Nov 2, 2019
1 parent 09f3dbe commit 43b7029
Showing 1 changed file with 4 additions and 0 deletions.
4 changes: 4 additions & 0 deletions drivers/hid/i2c-hid/i2c-hid-core.c
Original file line number Diff line number Diff line change
Expand Up @@ -447,8 +447,12 @@ static int i2c_hid_hwreset(struct i2c_client *client)
if (ret) {
dev_err(&client->dev, "failed to reset device.\n");
i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
goto out_unlock;
}

/* At least some SIS devices need this after reset */
ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);

out_unlock:
mutex_unlock(&ihid->reset_lock);
return ret;
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