Hi, On Thu, Oct 10, 2013 at 11:49:17AM -0400, Alan Stern wrote: > On Thu, 10 Oct 2013, Felipe Balbi wrote: > > > On Tue, Oct 08, 2013 at 10:28:29AM -0400, Alan Stern wrote: > > > Felipe: > > > > > > I've got an Android device that uses the omap2430 musb driver. It's > > > configured to go into device mode when it starts up, which I guess is > > > the normal thing for Android devices to do. > > > > > > Can you explain how to switch the controller over to host mode (and > > > back)? I tried writing "host" to the sysfs "mode" attribute, but all > > > that happened was an immediate crash and reboot. > > > > grounding ID pin should be enough. > > I can't ground the ID pin. The USB port is exposed through a > proprietary connector and cable; the far end of the cable has a normal > (not micro) type-A plug. (In case it matters, the device is a Nook > HD.) > > > If you're getting a crash when > > switching through sysfs, it's likely a bug in that kernel. Can you share > > the crash ? > > There's nothing to share. The device's screen goes all black and a > reboot begins right away. > > Admittedly, this is a pretty old kernel (3.0 vintage). Barnes & Noble > doesn't upgrade the the software for their devices very much. > > > > (Related to this, it is notable that the omap2430_musb_set_mode() > > > routine ignores its second argument, musb_mode. That looks awfully > > > strange, even if it is right.) > > > > it's strange because it's wrong :-) In all fairness OMAP2430 and onwards > > don't really need SW to switch between host and device roles, though. > > > > It's only good for testing when you have the wrong cable and still want > > to go to that role. > > That's exactly the situation I'm in (except perhaps for the testing > part -- it's hard to get much information out of a commercial device). IIRC the debugfs interface is suppposedly a little better. /me goes check the code here it goes, just wrote "force host" to /sys/kernel/debug/musb*/testmode Hopefully they have that enabled :-) -- balbi
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