imx8mp USB OTG/dual-role

[Jun Li]

Hi,

> -----Original Message-----
> From: Jacky Bai <ping.bai at nxp.com>
> Sent: Wednesday, August 31, 2022 9:18 AM
> To: tharvey at gateworks.com; linux-usb at vger.kernel.org; Linux ARM Mailing
> List <linux-arm-kernel at lists.infradead.org>; Jun Li <jun.li at nxp.com>
> Cc: Alexander Stein <alexander.stein at ew.tq-group.com>; Jun Li
> <jun.li at nxp.com>; Rikard Falkeborn <rikard.falkeborn at gmail.com>; Lucas
> Stach <l.stach at pengutronix.de>; Philippe Schenker
> <philippe.schenker at toradex.com>; Felipe Balbi <balbi at kernel.org>; Fabio
> Estevam <festevam at denx.de>; Marcel Ziswiler <marcel.ziswiler at toradex.com>;
> Shawn Guo <shawnguo at kernel.org>; Marek Vasut <marex at denx.de>; Francesco
> Dolcini <francesco.dolcini at toradex.com>; Aisheng Dong
> <aisheng.dong at nxp.com>; Sascha Hauer <s.hauer at pengutronix.de>;
> dl-linux-imx <linux-imx at nxp.com>; Pengutronix Kernel Team
> <kernel at pengutronix.de>
> Subject: RE: imx8mp USB OTG/dual-role
> 
> Jun, as we discussed before, any conclusion on how to handle the USB OTG
> ID pin in RM?

The NXP datasheet for iMX8MP already changed the ID pin name to be with _DNU
suffix, RM may be updated in next version.
If legacy ID is going to be used, any normal GPIO function can be selected
for it, extcon is well supported in dwc3 controller driver. 

More comments for Tim, see below...

> 
> 
> BR
> Jacky Bai
> 
> > Subject: imx8mp USB OTG/dual-role
> >
> > Greetings,
> >
> > I have an imx8mp board (imx8mp-venice-gw74xx) which has a DWC3 USB
> > host controller using imx8mp PHY
> > (drivers/phy/freescale/phy-fsl-imx8mq-usb.c fsl,imx8mp-usb-phy) and
> > DWC3 host controller core (drivers/usb/dwc3/core.c snps,dwc3) with
> > imx8mp glue (drivers/usb/dwc3/dwc3-imx8mp.c fsl,imx8mp-dwc3).
> >
> > One of the 2x USB 3.0 hosts is connected to a USB Type C connector
> > using a
> > TPS25821 USB power switch and config controller which handles the CC
> > pins on and VBUS enable as well as drives the mux sel pin of a
> > USB3 mux to route the USB SS pairs to the appropriate half of the Type
> > C connector. This device has no I2C or other management bus - only
> > VBUS, FAULT#, SINK#, and POL# outputs based on CC pins.
> >
> > I'm not clear how to describe this in the device-tree in order for it
> > to function as a dual-role controller for host vs device mode.
> >
> > The TPS25821 has a FAULT# signal that routes to IMX8MP GPIO1_IO13
> > pinmuxed as MX8MP_IOMUXC_GPIO1_IO13__USB1_OTG_OC and a SINK# signal
> > that routes to IMX8MP GPIO1_IO10 pinmuxed as
> > MX8MP_IOMUXC_GPIO1_IO10__USB1_OTG_ID. Additionally the VBUS output of
> > the TPS25821 also connected to the TypeC VBUS pin routes to the IMX8MP
> > USB1_VBUS pin.

So TPS25821 does not need a driver.

> >
> > I've noticed there are currently only 2 other IMX8MP boards in Linux
> > mainline that specify dr_mode="otg"; the DH electronics i.MX8M Plus
> > DHCOM SOM (imx8mp-dhcom-som.dtsi), and the Toradex i.MX8M Plus Verdin
> > SOM (imx8mp-verdin.dtsi). I'm not clear how these are hooked up or if
> > USB dual-role work on these currently. I did notice that

NXP iMX8MP EVK has not enabled type-C port due to the SS orientation
switch binding is still in discussion, but you don't need a SW control
in your case so you are okay here.

> > imx8mp-verdin.dtsi looks like it does not enable the phy or core via
> > status prop and uses invalid 'over-current-active-low' and
> 'disable-over-current' dt props.
> >
> > I am currently using the following with imx8mp-venice-gw74xx:
> >
> > /* USB1 - Type C front panel */
> > &usb3_phy0 {
> >         status = "okay";
> > };
> >
> > /* USB1 dwc3 glue */
> > &usb3_0 {
> >         fsl,over-current-active-low;
> >         status = "okay";
> > };
> >
> > /* USB1 dwc3 core */
> > &usb_dwc3_0 {
> >         pinctrl-names = "default";
> >         pinctrl-0 = <&pinctrl_usb1>;
> >         dr_mode = "otg";
> > };
> >
> > &iomuxc {
> >         pinctrl_usb1: usb1grp {
> >                 fsl,pins = <
> >
> > MX8MP_IOMUXC_GPIO1_IO13__USB1_OTG_OC    0x140
> >
> > MX8MP_IOMUXC_GPIO1_IO10__USB1_OTG_ID    0x140
> >                 >;
> >         };
> > };
> >
> > And currently v6.0-rc2 enumerates the host controller even without a
> > Type-C to host cable attached which tells me that OTG_ID isn't doing
> > its job. I vaguely recall some confusing statements on the IMX
> > community forum that these pins might not even be used on the IMX8MP.
> >
> > How should I be describing the device-tree for this scenario in order
> > to get dual-role behavior?

Could this dts work for you?

/* Config the "ID" pin iomux to be GPIO */

pinctrl_usb1: usb1grp {
                 fsl,pins = <
                      MX8MP_IOMUXC_GPIO1_IO13__USB1_OTG_OC    0x140
                      MX8MP_IOMUXC_GPIO1_IO10__GPIO1_IO10    0x140
          >;
 };

 extcon_usb: extcon_iddig {
                 compatible = "linux,extcon-usb-gpio";                                                                                                                                 
                 id-gpio = <&gpio1 10 GPIO_ACTIVE_HIGH>;
 };

 &usb_dwc3_0 {
         pinctrl-names = "default";
         pinctrl-0 = <&pinctrl_usb1>;
		 extcon = <&extcon_usb>
         dr_mode = "otg";
 };

Li Jun

> >
> > Best Regards,
> >
> > Tim