Re: [Qemu-devel] USB PCI host bus adapter hot plug

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 08/12/2014 04:05 PM, Alexey Kardashevskiy wrote:
> On 08/11/2014 03:59 PM, Gonglei (Arei) wrote:
>> Hi,
>>
>>> Subject: [Qemu-devel] USB PCI host bus adapter hot plug
>>>
>>> Hi!
>>>
>>> I noticed that QMP's "device_add usb-ehci,id=i2,bus=pci.0" fails on PCI
>>> hotplug. The same for pci-ohci and this is because their initfn() do
>>> "dc->hotpluggable   = false". So I removed those and now I can hotplug USB
>>> hosts but none of them is able to actually work:
>>>
>>> root@aiktest-le:~# echo 1 >/sys/bus/pci/rescan
>>> [   41.143062] ohci-pci 0000:00:01.0: init err (c8700000 0000)
>>> [   41.143133] ohci-pci 0000:00:01.0: can't start
>>> [   41.143227] ohci-pci 0000:00:01.0: startup error -75
>>> [   41.144202] ohci-pci 0000:00:01.0: init 0000:00:01.0 fail, -75
>>>
>>>
>>> root@aiktest-le:~# echo 1 >/sys/bus/pci/rescan
>>> [   43.691067] ehci-pci 0000:00:01.0: can't setup: -110
>>> [   43.692424] ehci-pci 0000:00:01.0: init 0000:00:01.0 fail, -110
>>>
>>>
>>> Why is that? Is QEMU just missing some bits or there is some fundamental
>>> issue which I just do not see? Thanks!
>>>
>> Cc'ing Gerd.
>>
>> Actually I have post a patch serials for supporting usb host adapter hotplugging,
>> Which has been involved in Gerd's (the USB mantainer) usb-next tree. Please see:
>> https://www.kraxel.org/cgit/qemu/log/?h=rebase/usb-next
>>
>> The function of usb host adapter hotplugging is ok. You are welcome to test it.
> 
> It does not work for me though. The device appears in the system but the
> driver fails to bring it up:
> 
> [root@localhost ~]# echo 1 >/sys/bus/pci/rescan
> 
> [   43.482378] pci 0000:00:01.0: BAR 0: assigned [mem
> 0x100a0000000-0x100a0000fff]
> [   43.488851] ehci-pci 0000:00:01.0: EHCI Host Controller
> 
> [   43.490153] ehci-pci 0000:00:01.0: new USB bus registered, assigned bus
> number 1
> [   43.504957] ehci-pci 0000:00:01.0: can't setup: -110
> 
> [   43.505028] ehci-pci 0000:00:01.0: USB bus 1 deregistered
> 
> [   43.507660] ehci-pci 0000:00:01.0: init 0000:00:01.0 fail, -110
> 
> [   43.507808] ehci-pci: probe of 0000:00:01.0 failed with error -110
> 
> 
> 
>> BTW, What's your guest os type?
> 
> Fedora20/ppc64 or Ubuntu14/ppc64le.
> 
> I tried your tree merged with
> https://github.com/mdroth/qemu/tree/spapr-pci-hotplug-ppc-next-cleanup2
> 
> I am adding PCIhotplug-on-PPC experts to the thread, may be they have ideas...


More precise - this fails:

drivers/usb/host/ehci-hcd.c:

int ehci_handshake(struct ehci_hcd *ehci, void __iomem *ptr,
                   u32 mask, u32 done, int usec)
{
        u32     result;

        do {
                result = ehci_readl(ehci, ptr);
                if (result == ~(u32)0)          /* card removed */
                        return -ENODEV;
                result &= mask;
                if (result == done)
                        return 0;
                udelay (1);
                usec--;
        } while (usec > 0);
        return -ETIMEDOUT; // <------------------
}




-- 
Alexey