On 21.01.2015 19:53, Bin Liu wrote: > 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 I have the same experience with 3.15. The switching is working when CONFIG_USB_MUSB_DUAL_ROLE is set and dr_mode = "otg". But since 3.16 it seems to be broken. Still had no time to bisect this. Yegor -- 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
