HID: i2c-hid: Add sleep between POWER ON and RESET

[mirror_ubuntu-zesty-kernel.git] / drivers / hid / i2c-hid / i2c-hid.c

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index 78fb32a7b103446136000c8ee9ac64cf7fba7054..ea3c3546cef7f81f0f1c82b996c3ed5ab9fb26ed 100644 (file)
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -426,6 +426,15 @@ static int i2c_hid_hwreset(struct i2c_client *client)
        if (ret)
                goto out_unlock;
 
+       /*
+        * The HID over I2C specification states that if a DEVICE needs time
+        * after the PWR_ON request, it should utilise CLOCK stretching.
+        * However, it has been observered that the Windows driver provides a
+        * 1ms sleep between the PWR_ON and RESET requests and that some devices
+        * rely on this.
+        */
+       usleep_range(1000, 5000);
+
        i2c_hid_dbg(ihid, "resetting...\n");
 
        ret = i2c_hid_command(client, &hid_reset_cmd, NULL, 0);