On Wed, Nov 25, 2009 at 1:33 PM, Rajaram R <rajaram.officemail@xxxxxxxxx> wrote: > On Wed, Nov 25, 2009 at 3:30 PM, Mandeep Sandhu > <mandeepsandhu.chd@xxxxxxxxx> wrote: >> Hi All, >> >> I have a basic doubt on root hubs. >> >> I'm working on a media SoC which has 1 USB interface which can >> function both as a host and a device (would this qualify for OTG? the >> datasheet doesn't mention OTG though) and an on-chip PHY. Here's an >> excerpt from the datasheet about the USB host controller: >> >> "The USB 2.0 Embedded Host Controller is fully compliant with the USB >> 2.0 specification and the Enhanced Host Controller Interface (EHCI) >> specification revision 1.0. The controller supports high-speed >> (480Mbps) transfers. The controller comprehends the high-speed, >> full-speed and low-speed data ranges providing compatibility with a >> full range of USB devices. The full-speed and low-speed operations are >> supported through the EHCI software stack via a transaction >> translation layer." >> >> Now my question is, does the EHCI also function as a root hub? As in >> the root hub is incorporated into the host controller? >> >> If I have to add another USB port to such a device, will it be >> possible to connect it to the existing root hub? >> >> I'm asking this because its mentioned that the host controller also >> has an on-chip PHY, and as I understand I'll have to connect my second >> port directly onto the USB bus and not to the PHY interface. Is my >> understanding correct? > > Can you point to the data sheet ? Can't, since it's not available in the public domain. Does the USB spec mandate that a host controller also function as a root hub? (http://en.wikipedia.org/wiki/Usb#Overview) Thanks, -mandeep > >> >> Thanks, >> -mandeep >> -- >> 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 >> > -- 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
