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Re: Bug#730482: linux-image-3.9.6: PCI/USB reset not being done on Geode LX800 / CS5536



Hi Kernel Maintainers,

Since the package doesn't exist this landed in the wrong place. Could 
you please have a look and take over the bug if useful?

Thanks,
Andrei

On Lu, 25 nov 13, 14:59:32, lkcl wrote:
> Package: linux-image-3.9.6
> Version: 3.9.6
> Severity: normal
> 
> 
> the "normal" reporting information is being removed because the report
> is being generated from an alternative non-SMTP-networked system
> 
> here's what has to be done to solve the problem:
> 
>     write_sys("/sys/bus/usb/devices/usb1/remove", "1")
>     write_sys("/sys/bus/usb/devices/usb2/remove", "1")
> 
>     write_sys("/sys/devices/pci0000:00/0000:00:0f.5/remove", "1")
>     write_sys("/sys/devices/pci0000:00/0000:00:0f.4/remove", "1")
>     time.sleep(5)
>     write_sys("/sys/devices/pci0000:00/pci_bus/0000:00/rescan", "1")
>     time.sleep(5)
> 
> the two devices are listed from lspci, here:
> 00:0f.4 USB controller: Advanced Micro Devices [AMD] CS5536 [Geode companion] OHC (rev 02)
> 00:0f.5 USB controller: Advanced Micro Devices [AMD] CS5536 [Geode companion] EHC (rev 02)
> 
> which correspond to the two "remove"s above.
> 
> this is basically an incredibly drastic PCI USB host controller reset
> which has to be done in between mountkernfs and udev.  it's therefore
> set up on an /etc/rc.S/S03 level script which carries out the resets
> that *should* be being done by the kernel modules themselves in the
> first place.
> 
> symptoms are as follows:
> 
> * put a USB 3G MiniPCIe modem into an alix6f2 LX800 board
> * ls /dev/ttyACM0
> * reboot (do NOT powercycle)
> * log in again
> * ls /dev/ttyACM0 - FAILS.
> 
> however if instead of a reboot a halt and power-cycle is carried out instead,
> the 2nd ls /dev/ttyACM0 SUCCEEDS.
> 
> it *also* succeeds even without a powercycle if the above drastic PCI device
> reset is carried out.
> 
> if however this is carried out *after* udev is allowed to pick things up
> then we have a bit of a problem, which is that e.g. other USB devices
> (such as USB memory sticks or USB-to-serial converters) suddenly find that
> in the middle of loading the kernel module the device just... disappears
> (because the USB hub it's connected to just got a kick in the nuts).
> 
> this has probably been a long-standing bug in the CS5536 PCI host controller
> code.  the reset should be being carried out at startup when the module
> is loaded.

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