[PATCH V2] usb: ehci-mx6: Enable OTG detection on imx8mm and imx8mn

[Adam Ford]

On Thu, Jan 13, 2022 at 6:49 PM Adam Ford <aford173 at gmail.com> wrote:
>
> On Thu, Jan 13, 2022 at 6:35 PM Adam Ford <aford173 at gmail.com> wrote:
> >
> > On Wed, Jan 12, 2022 at 2:17 AM Michael Walle <michael at walle.cc> wrote:
> > >
> > > Am 2022-01-11 17:52, schrieb Adam Ford:
> > > > On Tue, Jan 11, 2022 at 9:31 AM Michael Walle <michael at walle.cc> wrote:
> > > >>
> > > >> Hi,
> > > >>
> > > >> Am 2022-01-11 15:20, schrieb Adam Ford:
> > > >> > On Tue, Jan 4, 2022 at 2:32 AM Michael Walle <michael at walle.cc> wrote:
> > > >> >> > The imx8mm and imx8mn appear compatible with imx7d-usb
> > > >> >> > flags in the OTG driver.  If the dr_mode is defined as
> > > >> >> > host or peripheral, the device appears to operate correctly,
> > > >> >> > however the auto host/peripheral detection results in an error.
> > > >> >> >
> > > >> >> > The solution isn't just adding checks for imx8mm and imx8mn to
> > > >> >> > the check for imx7, because the USB clock needs to be running
> > > >> >> > to read from the USBNC_PHY_STATUS_OFFSET register or it will hang.
> > > >> >> >
> > > >> >> > The init_type in both priv and plat data are the same, so it doesn't
> > > >> >> > make sense to configure the data in the plat data and copy the
> > > >> >> > data to priv when priv can be configured directly.  Instead, rename
> > > >> >> > ehci_usb_of_to_plat to ehci_usb_dr_mode and call it from the
> > > >> >> > probe functions after the clocks are enabled, but before the data
> > > >> >> > is required.
> > > >> >> >
> > > >> >> > With that added, the additional checks for imx8mm and imx8mn will
> > > >> >> > allow reading the register to automatically determine the state
> > > >> >> > (host or device) of the OTG controller.
> > > >> >> >
> > > >> >> > Signed-off-by: Adam Ford <aford173 at gmail.com>
> > > >> >> > ---
> > > >> >> > V2:  Rename ehci_usb_of_to_plat to ehci_usb_dr_mode and call it
> > > >> >> >      from the probe after the clocks are enabled, but before
> > > >> >> >      the data is needed.
> > > >> >> >
> > > >> >> > diff --git a/drivers/usb/host/ehci-mx6.c b/drivers/usb/host/ehci-mx6.c
> > > >> >> > index 1bd6147c76..f2a34b7f06 100644
> > > >> >> > --- a/drivers/usb/host/ehci-mx6.c
> > > >> >> > +++ b/drivers/usb/host/ehci-mx6.c
> > > >> >>
> > > >> >> ..
> > > >> >>
> > > >> >> > @@ -639,10 +639,8 @@ static int mx6_parse_dt_addrs(struct udevice *dev)
> > > >> >> >
> > > >> >> >  static int ehci_usb_probe(struct udevice *dev)
> > > >> >> >  {
> > > >> >> > -     struct usb_plat *plat = dev_get_plat(dev);
> > > >> >> >       struct usb_ehci *ehci = dev_read_addr_ptr(dev);
> > > >> >> >       struct ehci_mx6_priv_data *priv = dev_get_priv(dev);
> > > >> >> > -     enum usb_init_type type = plat->init_type;
> > > >> >> >       struct ehci_hccr *hccr;
> > > >> >> >       struct ehci_hcor *hcor;
> > > >> >> >       int ret;
> > > >> >> > @@ -660,8 +658,6 @@ static int ehci_usb_probe(struct udevice *dev)
> > > >> >> >               return ret;
> > > >> >> >
> > > >> >> >       priv->ehci = ehci;
> > > >> >> > -     priv->init_type = type;
> > > >> >>
> > > >> >
> > > >> > Michael,
> > > >> >
> > > >> >> I'm not sure this is correct. There is also this:
> > > >> >> https://elixir.bootlin.com/u-boot/v2022.01-rc4/source/drivers/usb/host/usb-uclass.c#L407
> > > >> >>
> > > >> >
> > > >> > Further down in the code, you should see:
> > > >> >     priv->phy_type = usb_get_phy_mode(dev_ofnode(dev));
> > > >>
> > > >> But that is just fetching the mode from the device tree, the
> > > >> usb_setup_ehci_gadget() referenced above, change the mode during
> > > >> runtime by writing the plat->init_type and reprobing the device.
> > > >>
> > > >> >> Which won't work anymore. usb_setup_ehci_gadget() is called from
> > > >> >> usb_gadget_register_driver() in ci_udc.c. The latter is the one used
> > > >> >> on the imx, right? But I might be wrong. I'm still trying to figure
> > > >> >> out how this all works together, because I also try to get OTG
> > > >> >> running on the dwc3 driver. It looks like the ci_udc.c is special
> > > >> >> here, and I wonder how a transition to UCLASS_USB_GADGET_GENERIC
> > > >> >> might look like for this driver.
> > > >> >
> > > >> > This driver really isn't changing anything, it's just an order of
> > > >> > operations.
> > > >>
> > > >> It doesn't use the plat->init_type at all anymore, no?
> > > >
> > > > From what I could tell, the only thing that plat->init_type did was to
> > > > set priv->init_type.
> > > > The priv structure appears to do most of the work.
> > >
> > > but plat->init_type seems to change during runtime (by
> > > usb_setup_ehci_gadget()) and with this patch applied, it doesn't
> > > do that anymore.
> > >
> > > >> >  Previously there was a separate that was being called to
> > > >> > determine the init_type as being either a peripheral or host.  If it
> > > >> > wasn't explicitly set in the device tree, the helper function would
> > > >> > query a register, however, on the imx8mm and imx8mn platforms, the
> > > >> > clocks were not running which resulted in a hang.  What I've done is
> > > >> > simply move the helper function into the probe and have it run after
> > > >> > the clocks start.  In theory the register values will be the same as
> > > >> > they would be with the help function still in place.
> > > >> >
> > > >> > Both Tim Harvey and I have tested on an imx8mm and Fabio tested it on
> > > >> > an imx7.  For me, the peripheral mode worked when the ID pin of the
> > > >> > USB-OTG was not grounded.  When it was grounded, the system corrected
> > > >> > identified it as a host and I was able to mount a USB drive.
> > > >>
> > > >> Again, I'm missing something here, but the only user of
> > > >> usb_setup_ehci_gadget() is usb/gadget/ci_udc.c.
> > > >
> > > > I can't speak to what those functions do.   What are you suggesting
> > > > that I do differently?
> > >
> > > I'd start by seeing if/when usb_setup_ehci_gadget() is called and
> > > see if plat->init_type changes. If its not called, is it dead code
> > > then?
> >
> > I commented out the call to usb_setup_ehci_gadget(), and the gadget
> > driver still enumerated.
> > I'll push a V2 to remove it along with some subsequent patches to
> > update the defconfig, so others who want to use/test it don't have to
> > guess what config options are necessary.
> >
> > Thanks for catching that.
> >
>
> Simon,
>
> i went go to remove usb_setup_ehci_gadget(), but the header file has a
> TODO with your name on it, but the ci_udc river appears to be the only
> function to call it, and from what I can tell, the CI-UDC driver
> doesn't need this.
>
> /**
>  * usb_setup_ehci_gadget() - Set up a USB device as a gadget
>  *
>  * TODO(sjg at chromium.org): Tidy this up when USB gadgets can use driver model
>  *
>  * This provides a way to tell a controller to start up as a USB device
>  * instead of as a host. It is untested.
>  */
>
> If I remove the function call from the ci_udc.c driver, do you want
> this left in the header?  As it's written, the usb_setup_ehci_gadget()
> appears to attempt to override the plat->init_type, but this change is
> eliminating the need for the plat structure since it is pointless.
> From what I can tell the function is trying to force a re-probe with
> the plat->init_type redefined as a peripheral, but the code I want to
> use auto-detects the host/peripheral mode, rendering this pointless.
>

Michael,

It appears that the usb_setup_ehci_gadget() forces the USB driver into
peripheral mode regardless
of the device tree and/or the state of the register that detects the
pin, so I'm going to submit a V3 that keeps the helper function.
The helper function will not read the register to determine the
host/peripheral mode.  Instead, it will return UNKNOWN if the
device tree does not explicitly state the dr_mode.

If the device type is UNKNOWN, then the probe will call
ehci_usb_phy_mode after the clocks are started which will query
the register for the IP block to determine the state.  This way, we
don't break some of the functionality for forcing
peripheral mode if we intentionally activate a peripheral.

Tim & Fabio,

Would you mind re-testing?  I'm going to drop the added tags on the V3
because there is enough changes here and a small change
in behavior that I think it warrants re-test and/or re-review.

adam

> adam
>
> > adam
> >
> > > Sorry I just noticed this, while reviewing how this particular driver
> > > works, because I still like to find a working OTG driver in u-boot.
> > > I don't have any imx boards.
> > >
> > > -michael