Bug 6271

Most recent kernel where this bug did not occur: 2.6.15
Distribution: Kubuntu 5.10 (Breezy Badger)
Hardware Environment: Laptop MSI S270 (ATIIXP chipset) with mobile Sempron
Software Environment:
Problem Description:
When a USB to RS232 adapter is connected during booting and Legacy USB support
is activated in the BIOS, the system never displays
[OK] after the "Detecting and activating hardware" sentence. Then the keyboard
is still reacting (but you can not do anything to go on booting). In fact I had
to turn off my computer the hard way. Other USB devices (tested with USB
Bluetooth adapter, USB MMC cardreader and USB mouse) were activated fine by
"Detecting and activating hardware". Moreover the USB to serial converter works
well when connected after "Detecting and activating hardware" had finished.

The dmesg output (with "Legacy USB Support" activated) of the converter
connected when the system is already running is:
[17181800.648000] usb 1-2: new full speed USB device using ohci_hcd and address 2
[17181800.800000] usb 1-2: configuration #1 chosen from 1 choice
[17181800.908000] usbcore: registered new driver usbserial
[17181800.908000] drivers/usb/serial/usb-serial.c: USB Serial support registered
for generic
[17181800.908000] usbcore: registered new driver usbserial_generic
[17181800.908000] drivers/usb/serial/usb-serial.c: USB Serial Driver core
[17181800.920000] drivers/usb/serial/usb-serial.c: USB Serial support registered
for pl2303
[17181800.924000] pl2303 1-2:1.0: pl2303 converter detected
[17181800.924000] usb 1-2: pl2303 converter now attached to ttyUSB0
[17181800.924000] usbcore: registered new driver pl2303
[17181800.924000] drivers/usb/serial/pl2303.c: Prolific PL2303 USB to serial
adaptor driver

The (in my view important) dmesg parts when a adaptor is connected during
booting without Legacy USB support enabled:
[17179580.048000] usbcore: registered new driver usbserial
[17179580.048000] drivers/usb/serial/usb-serial.c: USB Serial support registered
for generic
[17179580.168000] input: ImPS/2 Logitech Wheel Mouse as /class/input/input2
[17179580.544000] usbcore: registered new driver usbserial_generic
[17179580.544000] drivers/usb/serial/usb-serial.c: USB Serial Driver core
[17179580.616000] drivers/usb/serial/usb-serial.c: USB Serial support registered
for pl2303
[17179580.800000] usb 2-1: new low speed USB device using ohci_hcd and address 2
[17179580.960000] usb 2-1: configuration #1 chosen from 1 choice
[17179580.964000] usbcore: registered new driver pl2303
[17179580.964000] drivers/usb/serial/pl2303.c: Prolific PL2303 USB to serial
adaptor driver
[17179581.220000] usb 1-2: new full speed USB device using ohci_hcd and address 3
[17179581.372000] usb 1-2: configuration #1 chosen from 1 choice
[17179581.376000] pl2303 1-2:1.0: pl2303 converter detected
[17179581.376000] usb 1-2: pl2303 converter now attached to ttyUSB0
[17179581.376000] usbcore: registered new driver hiddev

Note that the previous kernel (2.6.15) had some problems with my laptop too. I
needed irqpoll as boot parameter otherwise USB did not work at all. The current
kernel behaves the same regardless whether I use irqpoll or not.

Current workaround: Disconnect the adaptor before booting and connect the
adaptor later or disable "Legacy USB Support" in the BIOS.

Steps to reproduce:
Enable "Legacy USB Support" in the BIOS.
Connect a serial to USB adaptor and try to boot 2.6.16