Re: [PATCH v2 04/11] usb: xhci: Add Intel cherrytrail extended cap / otg phy mux handling

[Hans de Goede]

Hi,

On 19-09-17 14:40, Mathias Nyman wrote:
> Hi,
>
> sorry about the long delay
>
> On 07.09.2017 18:49, Hans de Goede wrote:
> > Hi,
> >
> > On 07-09-17 15:14, Mathias Nyman wrote:
> > > On 05.09.2017 19:42, Hans de Goede wrote:
> > > > The Intel cherrytrail xhci controller has an extended cap mmio-range
> > > > which contains registers to control the muxing to the xhci (host mode)
> > > > or the dwc3 (device mode) and vbus-detection for the otg usb-phy.
> > > >
> > > > Having a mux driver included in the xhci code (or under drivers/usb/host)
> > > > is not desirable. So this commit adds a simple handler for this extended
> > > > capability, which creates a platform device with the caps mmio region as
> > > > resource, this allows us to write a separate platform mux driver for the
> > > > mux.
> > > I think it would be better to have one place where we add handlers for
> > > vendor specific extended capabilities.
> > >
> > > Something like xhci-vendor-ext-caps.c, or just xhci-ext-caps.c as
> > > there's a xhci-ext-caps.h header already
> > >
> > > We could walk through the capability list once and add the needed handlers.
> > > Something like:
> > >
> > > +int xhci_ext_cap_init(void __iomem *base)
> >
> > This will need to take a struct xhci_hcd *xhci param instead
> > as some of the ext_cap handling (including the cht mux code)
> > will need access to this.
>
> yes, sample code added in second patch for reference/testing.
>
> > So I see 2 options here (without making this function PCI specific)
> > 1) Add an u32 product_id field to struct xhci_hcd; or
> > 2) Use a quirk flag as my current code is doing.
> >
> > I'm fine with doing this either way, please let me know your preference.
>
> Lets go with the quirk for now, I'll sort that out later
>
> > Can you do a "git format-patch" of that and send it to me? If you
> > can give me that + your preference for how to check if we're
> > dealing with a cht xhci hcd in xhci_ext_cap_init I can do a v3
> > with your suggestions applied.
>
> Ended up modifying xhci_find_next_ext_cap() using id = 0 for
> the next capability in list. Patch attached,
>
> Second patch is just for reference how to use it.

Thank you for the patches, I'm working on prepping a v3 of
this series which includes and uses the first patch.

Regards,

Hans