On 11/25/2009 09:30 AM, Mandeep Sandhu 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?
Yes, it has root hub. Transaction translation layer is on this hub.
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?
Yes, you will have to connect simple hub on the USB interface.
Thanks, -mandeep -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@xxxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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