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

[Paul Kocialkowski <paul.kocialkowski@bootlin.com>]

Hi,

On Mon 15 Jul 19, 12:55, Jagan Teki wrote:
> On Mon, May 27, 2019 at 5:21 AM André Przywara <andre.przywara@arm.com> wrote:
> >
> > On 17/04/2019 12:28, Jagan Teki wrote:
> > > On Mon, Apr 15, 2019 at 1:52 PM Paul Kocialkowski
> > > <paul.kocialkowski@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@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@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
> 
> Sorry, I missed this. yes rework can be a fancy but it's been
> discussed months back so I was expected to have this meaningful rework
> patch in-between so-that it would eventually reviewed and may plan for
> this MW.

Oh, has anyone started work in this direction so far?

> Having said that I'm not so interested to go with ifdef code in dm
> driver

Do you have a better option than ifdef to suggest for now?

> ( which we filter many thing before). better have a sample
> rework patch which still can review know.

I'm afraid I don't follow what you mean with that.

Cheers,

Paul

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com