[RFCv2 usb-next 0/3] initialize (multiple) PHYs in xhci-plat

[Chunfeng Yun]

Hi Martin,

On Thu, 2017-07-13 at 12:59 +0200, Martin Blumenstingl wrote:
> This series is the outcome of a discussion with Felipe Balbi,
> see [0] and [1].
> The quick-summary of this is:
> - dwc3 already takes one USB2 and one USB3 PHY and initializes these
>   correct
> - some other HCI platform drivers (like ehci-platform.c, xhci-mtk.c and
>   ohci-platform.c) do not have a limitation on the number of PHYs - they
>   support one PHY per actual host port
> - Amlogic Meson GXL and GXM SoCs come with a dwc3 IP block which has two
>   or three USB2 ports enabled on the internal root-hub. The SoCs also
>   provide separate USB2 PHYs, one per port. All USB2 PHYs (which are
>   internally "connected" to the dwc3 roothub) need to be powered on,
>   otherwise USB devices cannot be enumerated (even if just one PHY is
>   disabled and if the device is plugged into another, enabled port)
> 
> In my first attempt to get USB supported on the GXL and GXM SoCs I tried
> to work-around the problem that I could not pass multiple PHYs to the
> dwc3 controller.
> This was rejected by Rob Herring (which was definitely the thing to do in
> my opinion), see [2]
> 
> This series adds a new "platform-roothub". This can be configured through
> devicetree by passing a child-node with "reg = <0>" to the USB
> controller. Additionally there has to be a child-node for each port on
> the root-hub. Each of the child-nodes takes a "phys" and "phy-names"
> property. This allows modeling the root-hub in devicetree similar to the
> USB device binding (documented in devicetree/bindings/usb/usb-device.txt)
> This avoids and backwards-compatibility problems (which was a concern
> regardless of the solution, see [3]) since the binding for the root-hub
> was previously not specified (and we're not using the "phys" property of
> the controller, which might have served different purposes before,
> depending on the drivers).
> 
> Additionally this integrates the new platform-roothub into xhci-plat.c
> which automatically enables it for the dwc3 driver (in host-mode).
> 
How to handle the phy0(one u2phy and one u3phy) when port1 support
dual-role mode? leave them to peripheral side as felipe suggested
before? If so, no port1 node for roothub, is there any problem when
change the port1 to host-only mode?
 
> 
> Changes since RFCv1 at [4]:
> - split the usb-xhci dt-binding documentation into a separate patch
> - fixed a typo ("usb-phy" -> "phys" in the dt-binding example)
> - rebased to apply against latest usb-next
> 
> 
> [0] http://lists.infradead.org/pipermail/linux-amlogic/2017-January/001945.html
> [1] http://lists.infradead.org/pipermail/linux-amlogic/2017-January/001947.html
> [2] http://lists.infradead.org/pipermail/linux-amlogic/2016-November/001818.html
> [3] http://lists.infradead.org/pipermail/linux-amlogic/2017-January/001948.html
> [4] http://marc.info/?l=linux-usb&m=148414866303604&w=2
> 
> 
> Martin Blumenstingl (3):
>   dt-bindings: usb: add the documentation for USB root-hub
>   usb: host: add a generic platform USB roothub driver
>   usb: host: xhci: plat: integrate the platform-roothub
> 
>  .../devicetree/bindings/usb/usb-roothub.txt        |  46 +++++++
>  Documentation/devicetree/bindings/usb/usb-xhci.txt |   7 +
>  drivers/usb/host/Kconfig                           |   4 +
>  drivers/usb/host/Makefile                          |   2 +
>  drivers/usb/host/platform-roothub.c                | 146 +++++++++++++++++++++
>  drivers/usb/host/platform-roothub.h                |  14 ++
>  drivers/usb/host/xhci-plat.c                       |  27 +++-
>  drivers/usb/host/xhci.h                            |   2 +
>  8 files changed, 247 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/devicetree/bindings/usb/usb-roothub.txt
>  create mode 100644 drivers/usb/host/platform-roothub.c
>  create mode 100644 drivers/usb/host/platform-roothub.h
>