Documentation/usb/ehci.rst

5 27-Dec-2002
8 USB 2.0-capable host controller hardware.  The USB 2.0 standard is
11     - "High Speed" 480 Mbit/sec (60 MByte/sec)
12     - "Full Speed" 12 Mbit/sec (1.5 MByte/sec)
13     - "Low Speed" 1.5 Mbit/sec
15 USB 1.1 only addressed full speed and low speed.  High speed devices
23 (TT) in the hub, which turns low or full speed transactions into
24 high speed "split transactions" that don't waste transfer bandwidth.
31 While usb-storage devices have been available since mid-2001 (working
34 appear to be on hold until more systems come with USB 2.0 built-in.
39 other changes to the Linux-USB core APIs, including the hub driver,
43 - David Brownell
56 --------------
72 ---------------
99     # modprobe ehci-hcd
103     # rmmod ehci-hcd
106 "ohci-hcd"  or "uhci-hcd".  In case of any trouble with the EHCI driver,
127 		usb-storage doing disk I/O; watch the request queues!)
138 but they may want to check for "usb_device->speed == USB_SPEED_HIGH".
139 High speed devices can do things that full speed (or low speed) ones
140 can't, such as "high bandwidth" periodic (interrupt or ISO) transfers.
171 --------------------
194 default ehci-hcd driver uses the minimum latency, which means that if
199 --------------------
201 To get even 20 MByte/sec transfer rates, Linux-USB device drivers will
207 going to waste more than half the USB 2.0 bandwidth.  Delays between the
226    to trigger "high bandwidth" modes.
229    More than standard 80% periodic bandwidth allocation is possible