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
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
158 overall system load.  Latency is also a performance concern.
171 --------------------
191 There's a minimum latency of one microframe (125 usec) for the host
193 of requests.  That latency is tunable; there's a module option.  By
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