30.09.2019 01:15, Peter Geis пишет: > Good Afternoon, > > So I have dug a bit further into it. > The tegra-udc driver defaults to host mode when set to otg. > If the tegra-udc driver is in host mode while plugged into another > host, the kernel will hard lock. > If the tegra-udc driver is in host mode with a device attached the > device enumerates correctly. > In this state, if you change the state to gadget, the driver goes into > a broken state. > The gadget side is in gadget mode, but the host does not enumerate the device. > > As it stands the code path for the tegra-udc driver is broken in OTG mode. > Without proper extcon support we can't support dynamic switching > correctly anyways. > My hack around method of retaining the phy in peripheral mode and > switching drivers to change modes only works because both code paths > are incomplete as well, and should not be relied upon. > > I think for the time being, the tegra-udc driver should check for > host, peripheral, or otg mode. > If it detects the device is set to otg mode, it should print an error > message describing the current situation and fail out. > > If I had a device to test against with an extcon capable port, I'd try > some more experimenting with the chipidea drivers to see if I can get > it to work. > > What do you think? > > Dmitry, > Do you have any devices to experiment with this? Hello Peter, I had Nexus 7 v2013 that supported OTG (IIRC), unfortunately it broke about a year ago. I also have Nexus 7 v2012, but it doesn't support OTG (AFAIK). So no, I don't have hardware to test OTG. > On Sat, Sep 28, 2019 at 11:36 PM Peter Chen <peter.chen@xxxxxxx> wrote: >> >> >>> >>> I've encountered an odd situation where the CI Dual Role driver hard locks the >>> kernel on the Ouya (Tegra 3). >>> I was attempting to set up manual mode switching in the kernel, as the Ouya lacks >>> hardware support for the ID pin and no voltage output on that port. >>> I found that the kernel was hard locking whenever I had the dr_mode = "otg" set in >>> the devicetree. >> >> It seems Tegra doesn't support host mode using chipidea driver. The ci_hdrc_tegra.c >> only supports device mode. Thierry, could you confirm that? >> >> Peter >> >>> No further output was seen on the console, and sysreq does not respond. >>> It occurs both in module and builtin mode. >>> >>> I have however found a workaround. >>> By setting the dual role usb device to: >>> compatible = "nvidia,tegra30-ehci", "nvidia,tegra30-udc"; and setting the assigned >>> phy to: >>> dr_mode = "peripheral"; >>> I can achieve rudimentary live switching of roles. >>> The device defaults to host mode, as the ehci driver enumerates first. >>> By unbinding the tegra-ehci driver and binding the tegra-udc driver, I can switch to >>> gadget mode. >>> The reverse also works. >>> The PHY driver does not appear to care if it is always in peripheral mode. >>> >>> Thank you for your time, >>> Peter Geis
