i2c: tiny-usb: 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.

Fixes: e8c76eed2ecd ("i2c: New i2c-tiny-usb bus driver")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: <stable@vger.kernel.org> # v2.6.22+
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250522064349.3823-2-wsa+renesas@sang-engineering.com

diff --git a/drivers/i2c/busses/i2c-tiny-usb.c b/drivers/i2c/busses/i2c-tiny-usb.c
index a18eab0992a1ddc335cad808ca1e5beb8a3396a7..57dfe5f1a7d9f324be0dc7f7735337ed0196460e 100644 (file)
--- a/drivers/i2c/busses/i2c-tiny-usb.c
+++ b/drivers/i2c/busses/i2c-tiny-usb.c
@@ -139,6 +139,11 @@ out:
        return ret;
 }
 
+/* prevent invalid 0-length usb_control_msg */
+static const struct i2c_adapter_quirks usb_quirks = {
+       .flags = I2C_AQ_NO_ZERO_LEN_READ,
+};
+
 /* This is the actual algorithm we define */
 static const struct i2c_algorithm usb_algorithm = {
        .xfer = usb_xfer,
@@ -247,6 +252,7 @@ static int i2c_tiny_usb_probe(struct usb_interface *interface,
        /* setup i2c adapter description */
        dev->adapter.owner = THIS_MODULE;
        dev->adapter.class = I2C_CLASS_HWMON;
+       dev->adapter.quirks = &usb_quirks;
        dev->adapter.algo = &usb_algorithm;
        dev->adapter.algo_data = dev;
        snprintf(dev->adapter.name, sizeof(dev->adapter.name),