Hi Yegor, On Thu, Jan 22, 2015 at 08:37:45AM +0100, Yegor Yefremov wrote: > 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. I just gave 3.15 a quick try, and it looks like it can now detect when the device is acting as a gadget, but the host mode is not working at all. That's a good lead though, I'll dig more into the older versions and see if some are working better than others. Thanks! Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
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