media: usb: hdpvr: disable zero-length read messages

This driver passes the length of an i2c_msg directly to
usb_control_msg(). If the message is now a read and of length 0, it
violates the USB protocol and a warning will be printed. Enable the
I2C_AQ_NO_ZERO_LEN_READ quirk for this adapter thus forbidding 0-length
read messages altogether.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

drivers/media/usb/hdpvr/hdpvr-i2c.c

@@ -165,10 +165,16 @@ static const struct i2c_algorithm hdpvr_algo = {
 	.functionality = hdpvr_functionality,
 };
 
+/* prevent invalid 0-length usb_control_msg */
+static const struct i2c_adapter_quirks hdpvr_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN_READ,
+};
+
 static const struct i2c_adapter hdpvr_i2c_adapter_template = {
 	.name   = "Hauppauge HD PVR I2C",
 	.owner  = THIS_MODULE,
 	.algo   = &hdpvr_algo,
+	.quirks = &hdpvr_quirks,
 };
 
 static int hdpvr_activate_ir(struct hdpvr_device *dev)