[U-Boot] [linux-sunxi] [PATCH] phy: sun4i-usb: Fix PHY0 routing and passby configuration for MUSB

[André Przywara]

On 17/04/2019 12:28, Jagan Teki wrote:
> On Mon, Apr 15, 2019 at 1:52 PM Paul Kocialkowski
> <paul.kocialkowski at bootlin.com> wrote:

Hi,

>> Le vendredi 12 avril 2019 à 14:49 +0530, Jagan Teki a écrit :
>>> On Thu, Mar 14, 2019 at 4:08 PM Paul Kocialkowski
>>> <paul.kocialkowski at bootlin.com> wrote:
>>>> Recent Allwinner platforms (starting with the H3) only use the MUSB
>>>> controller for peripheral mode and use HCI for host mode. As a result,
>>>> extra steps need to be taken to properly route USB signals to one or
>>>> the other. More precisely, the following is required:
>>>> * Routing the pins to either HCI/MUSB (controlled by PHY);
>>>> * Enabling USB PHY passby in HCI mode (controlled by PMU).
>>>>
>>>> The current code will enable passby for each PHY and reroute PHY0 to
>>>> MUSB, which is inconsistent and results in broken USB peripheral support.
>>>>
>>>> Passby on PHY0 must only be enabled when we want to use HCI. Since
>>>> host/device mode detection is not available from the PHY code and
>>>> because U-Boot does not support changing the mode dynamically anyway,
>>>> we can just mux the controller to MUSB if it is enabled and mux it to
>>>> HCI otherwise.
>>>>
>>>> This fixes USB peripheral support for platforms with PHY0 dual-route,
>>>> especially H3/H5 and V3s.
>>>>
>>>> Signed-off-by: Paul Kocialkowski <paul.kocialkowski at bootlin.com>
>>>> ---
>>>>  drivers/phy/allwinner/phy-sun4i-usb.c | 14 +++++++++++++-
>>>>  1 file changed, 13 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/phy/allwinner/phy-sun4i-usb.c b/drivers/phy/allwinner/phy-sun4i-usb.c
>>>> index f206fa3f5d48..4f1c7e519d71 100644
>>>> --- a/drivers/phy/allwinner/phy-sun4i-usb.c
>>>> +++ b/drivers/phy/allwinner/phy-sun4i-usb.c
>>>> @@ -302,9 +302,21 @@ static int sun4i_usb_phy_init(struct phy *phy)
>>>>                                     data->cfg->disc_thresh, PHY_DISCON_TH_LEN);
>>>>         }
>>>>
>>>> +#ifdef CONFIG_USB_MUSB_SUNXI
>>>> +       /* Needed for HCI and conflicts with MUSB, keep PHY0 on MUSB */
>>>> +       if (usb_phy->id != 0)
>>>> +               sun4i_usb_phy_passby(phy, true);
>>>> +
>>>> +       /* Route PHY0 to MUSB to allow USB gadget */
>>>> +       if (data->cfg->phy0_dual_route)
>>>> +               sun4i_usb_phy0_reroute(data, true);
>>>> +#else
>>>>         sun4i_usb_phy_passby(phy, true);
>>>>
>>>> -       sun4i_usb_phy0_reroute(data, true);
>>>> +       /* Route PHY0 to HCI to allow USB host */
>>>> +       if (data->cfg->phy0_dual_route)
>>>> +               sun4i_usb_phy0_reroute(data, false);
>>>> +#endif
>>>
>>> I think we can manage this route and passby dynamically by detecting
>>> id since we have dr_mode verify the MUSB host or peripheral via
>>> usb_get_dr_mode, any chance to try that way?
>>
>> Oh, I didn't know that U-Boot has support for usb_get_dr_mode these
>> days. Thanks!
>>
>> So far, the sunxi port has been using Kconfig to distinguish between
>> host/device (unless I'm mistaken?) so I feel like this should be a
>> separate follow-up patch to convert the sunxi MUSB glue + PHY to
>> detecting dr_mode using usb_get_dr_mode. This feels like a significant
>> rework, too.
> 
> Yes.
> 
>>
>> Also, how should we handle the OTG case? I'm not sure we can support
>> having both musb host and gadget built-in at this point. But that would
>> certainly be welcome as part of the rework, too.
>>
>> What do you think?
> 
> You mean handling dr_mode at runtime.
> 
> If yes, It is bit new where we can register the musb as UCLASS_MISC
> wrapper and decide to bind driver for host and peripheral by decoding
> dr_mode. and indeed host should register with UCLASS_USB and
> peripheral with UCLASS_USB_GADGET_GENERIC.
> 
> I tried this wrapper before, not placed in-between because of other
> work but TI musb has similar code to manage this
> drivers/usb/musb-new/ti-musb.c

Before we go wild with any fancy rework, can we possibly take this patch
as it? As I realised, this is basically a better version of the patch I
sent two weeks ago [1]. I tried Paul's patch back then, but was missing
the phys property in the DT, which I addressed in patch 2/2.

So I would appreciate if we can take this patch, as it solves a real
problem (upper USB port not working) on many Pine64 boards (given the
small DT change is in place). And on those boards the OTG functionality
is not really feasible anyway, as VBUS is either permanently enabled or
at least tied to the other host port's supply, so we can't turn it off
for peripheral mode.

Cheers,
Andre.

[1] https://lists.denx.de/pipermail/u-boot/2019-May/369521.html