[PATCH 1/4] phy: sun4i-usb: support PHY0 on H3 in MUSB mode

[Icenowy Zheng]

19.01.2017, 22:34, "Maxime Ripard" <maxime.ripard at free-electrons.com>:
> On Wed, Jan 18, 2017 at 04:09:32AM +0800, Chen-Yu Tsai wrote:
>>  Hi,
>>
>>  On Wed, Jan 18, 2017 at 4:06 AM, Maxime Ripard
>>  <maxime.ripard at free-electrons.com> wrote:
>>  > On Wed, Jan 18, 2017 at 12:57:08AM +0800, Icenowy Zheng wrote:
>>  >>
>>  >>
>>  >> 17.01.2017, 16:06, "Maxime Ripard" <maxime.ripard at free-electrons.com>:
>>  >> > On Tue, Jan 17, 2017 at 03:14:46AM +0800, Icenowy Zheng wrote:
>>  >> >> The PHY0 on H3 can be wired either to MUSB controller or OHCI/EHCI
>>  >> >> controller.
>>  >> >>
>>  >> >> The original driver wired it to OHCI/EHCI controller; however, as the
>>  >> >> code to use PHY0 as OHCI/EHCI is missing, it makes the PHY fully
>>  >> >> unusable.
>>  >> >>
>>  >> >> Rename the register (according to its function and the name in BSP
>>  >> >> driver), and remove the code which wires the PHY0 to OHCI/EHCI, as MUSB
>>  >> >> can support both peripheral and host mode (although the host mode of
>>  >> >> MUSB is buggy).
>>  >> >
>>  >> > Can you elaborate on that? What's wrong with it?
>>  >>
>>  >> The configuration is at bit 0 of register 0x20 in PHY.
>>  >>
>>  >> When the PHY is reseted, it defaults as MUSB mode.
>>  >>
>>  >> However, the original author of the H3 PHY code seems to be lack of
>>  >> this knowledge (He named it PHY_UNK_H3), and changed the PHY to HCI
>>  >> mode.
>>  >>
>>  >> I just removed the code that wires it to HCI mode, thus it will work
>>  >> in MUSB mode, with my sun8i-h3-musb patch.
>>  >
>>  > I have no idea what you mean by MUSB mode.
>>  >
>>  > Do you mean that the previous code was only working in host mode, and
>>  > now it only works in peripheral?
>>
>>  From what I understand, with the H3, Allwinner has put a mux
>>  in front of the MUSB controller. The mux can send the USB data
>>  to/from the MUSB controller, or a standard EHCI/OHCI pair.
>>  This register controls said mux.
>>
>>  This means we can use a proper USB host for host mode,
>>  instead of the limited support in MUSB.
>
> But musb can still operate as a host, right?

Yes!

>
> Thanks!
> Maxime
>
> --
> Maxime Ripard, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com