* Markus Pargmann <mpa@xxxxxxxxxxxxxx> [140214 02:05]: > Hi, > > On Thu, Feb 13, 2014 at 03:25:52PM -0800, Tony Lindgren wrote: > > * Markus Pargmann <mpa@xxxxxxxxxxxxxx> [140213 15:16]: > > > Hi, > > > > > > On Thu, Feb 13, 2014 at 02:54:38PM -0800, Tony Lindgren wrote: > > > > * Markus Pargmann <mpa@xxxxxxxxxxxxxx> [140111 06:03]: > > > > > The PMIC is using usb0 vbus line as power source. It is also connected > > > > > to the am335x processor as vbus sense. But there is no possibility to > > > > > pullup usb0 vbus to operate as host. This patch fixes the dr_mode of usb0. > > > > > > > > That's the MUSB? AFAIK it's not possible to operate MUSB in peripheral > > > > only mode because the hardware does what it wants based on the ID > > > > pin state. > > > > > > Yes that's MUSB. The am335x reference manual describes that it is > > > possible to force peripheral/host mode by setting bit 7 (IDDIG_MUX) in > > > register USBnMODE to 1. Then it uses the bit written in bit 8 (IDDIG) of > > > register USBnMODE to set host/peripheral mode. > > > > OK > > > > > I am not sure if the driver supports it yet but I think the DTS should > > > contain the correct mode nevertheless, especially to avoid starting the > > > otg loops in the musb driver. > > > > Well there's one more thing to consider.. I think in the OTG role change > > case the VBUS is still driven externally from the original host, so the > > lack of VBUS does not always mean that host mode should be disabled. > > I thought more about the hardware description than the possible role > changes through software protocols. In a hardware perspective, this USB > port is only in peripheral mode, as it can't drive VBUS. However is > there any support for role change protocols in the kernel yet? There's some to trigger it, if you grep -ri hnp drivers/usb/ you'll see some references to it. > Perhaps we have to add a seperate DT binding for usb role changes when > they are supported. This would help to describe the hardware > capabilities (host, peripheral or OTG) and the role change protocols > supported. Yeah it might be worth discussing on the USB list what's the best way to deal with all that. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
