Re: [PATCH V3] xhci: Reset TI USB controller on xhci shutdown

[Wen Xiong <wenxiong@linux.ibm.com>]

> 
> I tried to make this code a bit more "proper", by moving the
> pci_reset_function_locked() call to xhci-pci.c from xhci.c.
> 
> I found that when I actually run this, I get a warning from PCI:
> 
>   unlocked secondary bus reset via: __pci_reset_function_locked
> 

Thanks for your reviewing!
Can we do?
if device is TI/0x8241 device, we just reset it in xhci-pci.c.
We don't need to bother other USB devices.

Thanks,
Wendy
> Bjorn, any tips what would be a proper way to whack a malfunctioning
> PCI device with a heavy hammer to ensure it will work after kexec?
> Seems we have pci_reset_function(), which locks the parent bridge for
> us, but it also preserves some "state". Do we want that?
> 
> I'm also starting to wonder if we shouldn't do this reset after kexec,
> to cover for kdump. Or maybe both, because shutdown() is supposed to
> quiesce the chip and keep it from doing DMA, and we have no idea what
> such chip is doing (if anything) when it refuses to halt.
> 
> Thanks,
> Michal
> 
>> [...]
>> +	/*
>> +	 * TI xHCI controllers fail to initialize in a kexec
>> +	 * kernel without a PCI function reset
>> +	 */
>> +	if (err && (xhci->quirks & XHCI_RESET_ON_SHUTDOWN))
>> +		pci_reset_function_locked(to_pci_dev(hcd->self.sysdev));
>> [...]