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

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  Re: [linux-sunxi] [PATCH v3 0/5] Add dual-role OTG support for  Allwinner H3 Chen-Yu Tsai <wens@csie.org> - 2017-03-07 04:00 +0100

#1593869 — Re: [linux-sunxi] [PATCH v3 0/5] Add dual-role OTG support for Allwinner H3

On Tue, Mar 7, 2017 at 8:24 AM, Icenowy Zheng <icenowy@aosc.xyz> wrote:
>
>
> 07.03.2017, 07:48, "Ondřej Jirman" <megous@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.

Sounds like the board is getting back-powered from VBUS through the enabled
current regulator. Given that you have it connected to the PC, which I assume
means peripheral mode, the bigger issue is why is VBUS enabled in peripheral
mode? It should never ever be so.


Regards
ChenYu

> 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(-)
>
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