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

[Paul Kocialkowski]

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.

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?

Cheers,

Paul

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