Hi, On Wed, Jan 21, 2015 at 10:06 AM, Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote: > Hi Felipe, > > I'm currently working on a custom AM335x-based board, that has a OTG > connector wired to one of the musb controlers, and Linux 3.17 > > This OTG connector seems to behave in a weird way when it comes to > switching from one role to another: > > - The host mode works with CONFIG_USB_MUSB_DUAL_ROLE set, only if > the dr_mode is set to host in the DT, and only if we plug the USB > device after the kernel has booted. Otherwise, even though the > controller seems to be set up as host in the kernel logs, it > doesn't work. When DR-mode is set to otg, DRVVBUS is not high > which surely doesn't help, but there might be some other issues. > > - The gadget mode works with CONFIG_USB_MUSB_DUAL_ROLE, if dr_mode > is set to otg and not host (obviously), and only if we plug the > USB cable after the kernel has booted. > > - The gadget mode works with CONFIG_USB_MUSB_GADGET, and with > dr_mode set to otg, even if we cold plug the device. > > - As you might expect from the two first items, the runtime > switching from gadget to host when CONFIG_USB_MUSB_DUAL_ROLE is > set and dr_mode is set in otg doesn't work either. > > It looks like it's only waiting for an interrupt to occur to read the > ID pin state, without reading its initial value, which would explain > why both the host and gadget enumerate only when a device/cable is > hotplugged, and that there's some configuration bits that differ > whenever dr_mode changes, but I couldn't really see anything standing > out in the driver nor the datasheet. > > Have you already experienced something alike with that driver? I don't use vanilla mainline kernel very often, but I don't have such hotplug issues with TI 3.12/14 kernels [1]. I only use CONFIG_USB_MUSB_DUAL_ROLE though. [1] git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git, branch remote/origin/linux-3.14.y Regards, -Bin. > > Thanks, > Maxime > > -- > Maxime Ripard, Free Electrons > Embedded Linux, Kernel and Android engineering > http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
