Hi, in my understanding, the statement: "The full-speed and low-speed operations are supported through the EHCI software stack via a transaction translation layer." mean that as many other usb controller, no hardware ttl is provided. So i see two possibilities: - Use the ttl in software (as datasheet say), perhaps already provided with some kind of libraries by your vendor or - Use an usb hub, so with an hw ttl. Have a good day --- Mer 25/11/09, Mandeep Sandhu <mandeepsandhu.chd@xxxxxxxxx> ha scritto: > Da: Mandeep Sandhu <mandeepsandhu.chd@xxxxxxxxx> > Oggetto: basic doubt on root hubs (on an embedded SoC) > A: "linux-usb" <linux-usb@xxxxxxxxxxxxxxx> > Data: Mercoledì 25 novembre 2009, 08:30 > 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? > > 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
