[PATCH 4/6] usb: xhci-pci: Move reset logic out of XHCI core

[Samuel Holland]

On 2/8/21 5:43 AM, Marek Vasut wrote:
> On 2/8/21 6:57 AM, Samuel Holland wrote:
>> Resetting an XHCI controller inside xhci_register undoes any register
>> setup performed by the platform driver. And at least on the Allwinner
>> H6, resetting the XHCI controller also resets the PHY, which prevents
>> the controller from working. That means the controller must be taken out
>> of reset before initializing the PHY, which must be done before calling
>> xhci_register.
>>
>> The logic in the XHCI core was added to support the Raspberry Pi 4
>> (although this was not mentioned in the commit log!), which uses the
>> xhci-pci platform driver. Move the reset logic to the platform driver,
>> where it belongs, and where it cannot interfere with other platform
>> drivers.
> 
> Are there any other XHCI drivers using the XHCI core code which might
> stop resetting correctly due to this patch ?

Since commit 0b80371b350e was merged, the only new call to xhci_register
is in USB_MTU3. Neither the binding for "mediatek,mtu3" nor any device
tree node containing that compatible string has a "resets" property. And
there have been no calls to reset_(de)assert since then, either. So I do
not see any other drivers that would be likely to break.

Samuel