Linux kernel module patch for Prolific PL-2303X USB-serial adapter

The following patch modifies the driver for the Prolific PL-2303 USB-serial adapter to add support for the highly similar but incompatible PL-2303X adapter. The PL-2303X has the same vendor ID and product ID as the older PL-2303, which means that it will be incorrectly detected as a PL-2303 by the driver currently in the Linux kernel. Attempting to use a PL-2303X as a PL-2303 simply results in an inability to transfer data through the serial port. In other words, nothing happens. This patch autodetects whether a PL-2303 or a PL-2303X is used and changes the initialisation sequence accordingly.

The PL-2303X can be distinguished from a PL-2303 by checking bMaxPacketSize0 for the device using lsusb -v -d 067b:2303 (as root). If bMaxPacketSize0 is 64, you probably have a PL-2303X and need this patch.

This patch has been written for and tested on the current SuSE 9.1 kernel (2.6.5-7.111.19-default) on i686. It is also reported to work on kernel version 2.4.28.

To apply the patch, execute

patch -u drivers/usb/serial/pl2303.c
pl2303x.patch

in your Linux source root directory.

Download the patch (3 KB)
See instructions below to compile and install.

Download precompiled kernel module for SuSE 9.1 kernel 2.6.5-7.111.19-default (21 KB)
Copy to

/lib/modules/`uname
-r`/kernel/drivers/usb/serial/

to install. This precompiled module will probably not work on any other kernel than the version it was compiled for.

Download precompiled kernel module for SuSE 9.1 kernel 2.6.4-52-default (22 KB) (supplied by Raghu Sunderam)
Copy to

/lib/modules/`uname
-r`/kernel/drivers/usb/serial/pl2303.ko

to install. This precompiled module will probably not work on any other kernel than the version it was compiled for.

This patch has only been tested on a few machines; use it at your own risk. I take no responsibility for any damage caused by this patch, and so on.

The main kernel tree includes PL-2303X support starting from 2.6.8 (I can confirm that PL-2303X works on 2.6.11rc2 without my patch), making this patch unnecessary.

Detailed patch installation instructions (SuSE 9.1)

The following instructions assume that you are using the default kernel provided by SuSE. Users of other SuSE kernel packages should substitute their kernel package name instead of kernel-default.

Ensure that the kernel package and the kernel source package for the currently running kernel are installed. Install (e.g. using YaST) and reboot as needed. The commands uname -r, rpm -q kernel-source and rpm -q kernel-default should all return the same version number.
Ensure that packages make, patch and gcc are installed.
Install the patch (all the following are performed as root):

cd /usr/src/linux
patch -u drivers/usb/serial/pl2303.c (directory containing patch file)/pl2303x.patch

Recompile the modules.

make cloneconfig
make modules_prepare (kernel version 2.6.5-7.75 and later only)
cd drivers/usb/serial/
make -C /usr/src/linux M=$(pwd)

Install the recompiled PL-2303X module.

If the old PL-2303 module is still loaded, unload it: rmmod pl2303
cp pl2303.ko /lib/modules/`uname -r`/kernel/drivers/usb/serial/
The kernel module should be automatically loaded by hotplug when a PL-2303X is connected.

Red Hat drivers

These drivers (17 KB) (apparently from Prolific) were provided by Alex K. They seem to be for Red Hat 7.3, 8 and 9. I have not tested these drivers; I am merely mirroring them as I can't find them elsewhere on the Net. Use them at your own risk.

Jan Lönnberg Web Site

Page last updated by Jan Lönnberg 2005-01-23.