Hello Tim, Am Freitag, 16. September 2022, 20:43:54 CEST schrieb Tim Harvey: > Greetings, > > I'm wondering if anyone has done any work to get dual-role USB working > for the IMX8MP (or any other dwc3 host based board) and how they went > about it if so. > > The imx8mp-venice-gw74xx has dual-role support through a USB Type-C > connector with a TPS25821 (driverless) that monitors the CC signals > and manages VBUS, as well as asserts gpio's: > FAULT# - pinmuxed to OC pin > SINK# - used as GPIO for role > POL# - used for SS mux to connector > > For linux this is managed with a usb-role-switch dt prop and a > connector node with compatible of gpio-usb-b-connector and id-gpios > [1]. I did not see anything like that in use in U-Boot for dwc3 hosts > but perhaps I was looking in the wrong place. > > For U-Boot I can get this type-C connector to work in host mode only > by changing dr_mode="otg" to dr_mode="host". With the default dt prop > dr_mode=otg dwc3-generic-peripheral is bound instead of > dwc3-generic-host thus no host controller is found. > > It seems to me that dwc3_glue_bind needs support added to be able to > check id-gpios or vbus-gpios if usb-role-switch and something like > gpio-usb-b-connector or linux,extcon-usb-gpio are used. Does this > sound like the correct implementation? > > I notice that drivers/usb/host/xhci-dwc3.c which is a driver for the > dwc3 core (compatible snps,dwc3) and this does look at usb-role-swich > however this driver as a subnode of fsl,imx8mp-dwc3 (glue) does not > bind and perhaps that is an issue. In that driver usb-role-switch > causes the driver to use role-switch-default-mode for the default mode > which still does not look at an id/vbus pin so that would not be > feature complete either.
For imx8mp you probably need something like [1] to support usb-role-switch. But I am not aware how things are done in u-boot. Best regards, Alexander [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ commit/?id=a102f07e4edf0f1cf06bf9825ab10e26a29dd945 > Best Regards, > > TIm > 1 > https://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux.git/commit/? > h=for-next&id=c8a4192d238e9258ab0bc916b3c138a4722af215