Comment 666 for bug 88746

I applied the EHCI patch to 2.6.28.9 and the DVD writer worked *fine* since then. There were no device resets and no damaged media. (The OHCI patch was rejected with 2.6.28.9, so I assume it had been merged before that.)

Unfortunately, when I connected an OHCI device (a USB audio adapter) to the same (NEC) host controller as the (Samsung) DVD writer, hundreds of messages like this appeared in dmesg:

sr 10:0:0:0: [sr1] Result: hostbyte=0x05 driverbyte=0x00
end_request: I/O error, dev sr1, sector 6363180
Buffer I/O error on device sr1, logical block 1590795
lost page write due to I/O error on sr1
usb 1-2: reset high speed USB device using ehci_hcd and address 4
usb 1-2: reset high speed USB device using ehci_hcd and address 4
usb 1-2: reset high speed USB device using ehci_hcd and address 4
usb 1-2: reset high speed USB device using ehci_hcd and address 4

When these things happen, both the DVD writer and the audio adapter freeze. Programs like alsamixer or dvd+rw-mediainfo remain blocked in an uninterruptible state. Unloading and re-loading both ohci_hcd and ehci_hcd does not help. The devices have to be reconnected physically.

All the problems seem to start with this message:

ohci_hcd 0000:01:05.0: bad entry 20d00

After the message, the sound card stops responding and the DVD writer has only a few seconds left before the never-ending series of device resets begins.

BTW, lsusb freezes as well. (Haven't seen that before.) It surprises me that one misbehaving device (which is probably the Samsung drive) has such an impact on the whole host controller.