On Wed, Apr 29, 2020 at 01:26:50AM +0530, m...@kernel.org wrote:
> From: Manivannan Sadhasivam <m...@kernel.org>
>
> Add support for MaxLinear/Exar USB to Serial converters. This driver
> only supports XR21V141X series but provision has been made to support
> other series in future.
>
> This driver is inspired from the initial one submitted by Patong Yang:
>
> https://patchwork.kernel.org/patch/10543261/
>
> While the initial driver was a custom tty USB driver exposing whole
> new serial interface ttyXRUSBn, this version is completely based on USB
> serial core thus exposing the interfaces as ttyUSBn. This will avoid
> the overhead of exposing a new USB serial interface which the userspace
> tools are unaware of.
Nice work!
Some comments below:
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * MaxLinear/Exar USB to Serial driver
> + *
> + * Based on initial driver written by Patong Yang <patong....@gmail.com>
> + *
> + * Copyright (c) 2020 Manivannan Sadhasivam <m...@kernel.org>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/tty.h>
> +#include <linux/usb.h>
> +#include <linux/usb/serial.h>
> +
> +#include "xr_serial.h"
No need for a .h file for a single .c file.
> +static int xr_get_reg(struct usb_serial_port *port, u8 block, u16 reg,
> + u16 *val)
> +{
> + struct usb_serial *serial = port->serial;
> + struct xr_port_private *port_priv = usb_get_serial_port_data(port);
> + void *dmabuf;
> + int ret = -EINVAL;
> +
> + dmabuf = kmalloc(sizeof(reg), GFP_KERNEL);
So that is 2 bytes?
> + if (!dmabuf)
> + return -ENOMEM;
> +
> + if (port_priv->idProduct == XR21V141X_ID) {
> + /* XR21V141X uses custom command for reading UART registers */
> + ret = usb_control_msg(serial->dev,
> + usb_rcvctrlpipe(serial->dev, 0),
> + XR_GET_XR21V141X,
> + USB_DIR_IN | USB_TYPE_VENDOR, 0,
> + reg | (block << 8), dmabuf,
> + port_priv->reg_width,
> + USB_CTRL_SET_TIMEOUT);
> + }
> +
> + if (ret == port_priv->reg_width) {
> + memcpy(val, dmabuf, port_priv->reg_width);
But here you copy ->reg_width bytes in? How do you know val can hold
that much? It's only set to be 1, so you copy 1 byte to a 16bit value?
What part of the 16bits did you just copy those 8 bits to (hint, think
cpu endian issues...)
That feels really really odd and a bit broken.
> --- /dev/null
> +++ b/drivers/usb/serial/xr_serial.h
> @@ -0,0 +1,103 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
Are you sure about the "+"? I have to ask :)
> +
> +#ifndef __LINUX_USB_SERIAL_XR_SERIAL_H
> +#define __LINUX_USB_SERIAL_XR_SERIAL_H
As you will drop this file, just a general statement, no need for
__LINUX as this is all Linux :)
thanks,
greg k-h
