[linux-sunxi] [PATCH v3 0/5] Add dual-role OTG support for Allwinner H3

[Icenowy Zheng]

07.03.2017, 07:48, "Ondřej Jirman" <megous at megous.com>:
> Hi Icenowy,
>
> when I was trying to add OTG support I found an issue with powercycling.
> When I have USB cable connecting PC and the OTG port on the SBC, when
> the board enables the vbus, it would become impossible to power cycle
> the board after poweroff. The reason being that when vbus is enabled,
> the board is powered from the OTG port even if you disconnect the barrel
> plug.
>
> Should kernel turn off the vbus before shutting down/restarting? What do
> you think?

It's a good problem.

I think this problem can be abstracted into:
Some regulators are needed to be shut down before system 
shutdown.

Is there any framework for it?

Mark,
I add you to recipients for the question above.

Thanks,
Icenowy

>
> regards,
>   o.
>
> Dne 6.3.2017 v 23:34 Icenowy Zheng napsal(a):
>>  Allwinner H3 have a its USB PHY0 routed to two USB controllers: one is
>>  a MUSB controller, which can work in peripheral mode, but works badly in
>>  host mode (several hardware will fail on the MUSB controller, even connect
>>  one MUSB controller in peripheral mode to another one in host mode cannot
>>  work); the other is a pair of EHCI/OHCI controller, which can work only
>>  in host mode, but have better compatibillity. The route is controlled in
>>  a register, which we have set it to HCI only when we do not know about
>>  it well.
>>
>>  Add support to route to the best controller according to current USB mode
>>  (host/peripheral).
>>
>>  Note: Currently even if hardware only support hostmode, we should still
>>  enable the MUSB controller, as it controls the USB mode. (Some this kind
>>  of hardware can also work in peripheral mode by settings in the sysfs
>>  node of MUSB, then connect it to another host via a USB Type-A to Type-A
>>  cable.)
>>
>>  Patch 1 changes the device tree binding to include the "pmu0" for HCI pair.
>>
>>  Patch 2 adds support for auto routing of PHY0. It's currently only enabled
>>  on H3, but it's easy to extend it to other SoCs which feature this
>>  route control.
>>
>>  Patch 3 adds necessary device tree nodes to the H3 DTSI file. Note: The
>>  phy is not bind for OHCI/EHCI0, as OHCI/EHCI drivers will keep the VBUS
>>  on. Only MUSB driver can properly handle a dual-role PHY.
>>
>>  Patch 4 enables USB OTG functionality on Orange Pi One board, which is
>>  the only H3 board I have that have proper OTG function. It's easy to
>>  enable OTG on other boards with their schematics.
>>
>>  Patch 5 enables USB OTG functionality on Orange Pi Zero board, as the
>>  board cannot output power on Vbus, I only enabled peripheral mode by
>>  default.
>>
>>  The USB PHY on V3s/A64 SoCs also feature this capability, and it will
>>  be soon enabled on these SoCs after this patchset is merged.
>>
>>  Icenowy Zheng (5):
>>    dt: bindings: add pmu0 regs for USB PHYs on Allwinner H3/V3s/A64
>>    phy: sun4i-usb: support automatically switch PHY0 route to MUSB/HCI
>>    ARM: dts: sun8i: h3: add usb_otg and OHCI/EHCI for usbc0 on H3
>>    ARM: dts: sun8i: h3: enable USB OTG on Orange Pi One
>>    ARM: dts: sun8i: h2+: enable USB OTG for Orange Pi Zero board
>>
>>   .../devicetree/bindings/phy/sun4i-usb-phy.txt | 1 +
>>   arch/arm/boot/dts/sun8i-h2-plus-orangepi-zero.dts | 14 ++++++
>>   arch/arm/boot/dts/sun8i-h3-orangepi-one.dts | 22 +++++++++-
>>   arch/arm/boot/dts/sun8i-h3.dtsi | 32 ++++++++++++++
>>   drivers/phy/phy-sun4i-usb.c | 50 ++++++++++++++--------
>>   5 files changed, 101 insertions(+), 18 deletions(-)