[PATCH V2] usb: host: xhci-plat: allow sysdev to inherit from ACPI

[Greg Kroah-Hartman]

On Tue, Sep 05, 2017 at 09:57:29AM -0400, Adam Wallis wrote:
> Currently, xhci_plat is not set up properly when the parent device is an
> ACPI node. The conditions that xhci_plat_probe should satisfy are
> 
> 1. xhci_plat comes from firmware
> 2. xhci_plat is child of a device from firmware (dwc3-plat)
> 3. xhci_plat is grandchild of a pci device (dwc3-pci)
> 
> Case 2 is covered when the child is an OF node (by checking
> sysdev->parent->of_node), however, an ACPI parent will return NULL in
> the of_node check and will thus not result in sysdev being set to
> sysdev->parent
> 
> [   17.591549] xhci-hcd: probe of xhci-hcd.6.auto failed with error -5
> 
> This change adds a check for ACPI to completely allow for condition 2.
> This is done by first checking if the parent node is of type ACPI (e.g.,
> dwc3-plat) and set sysdev to sysdev->parent if either of the two
> following conditions are met:
> 
> 1: If fwnode is empty (in the case that platform_device_add_properties
> was not called on the allocated platform device)
> 2: fwnode exists but is not of type ACPI (this would happen if
> platform_device_add_properties was called on the allocated device.
> Instead of type FWNODE_ACPI, you would end up with FWNODE_PDATA)
> 
> Cc: stable at vger.kernel.org #4.12.x
> Cc: stable at vger.kernel.org #4.13.x

What bug is this fixing that needs to go into the stable kernel trees?
Is this a regression, or a new feature for those versions?

thanks,

greg k-h