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
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 --------------
59 and interrupt transfers, including requests to USB 1.1 devices through
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76 ones from another driver, and that interrupt transfers can use periods
77 of one frame without risking data loss due to interrupt processing costs.
88 transactions (interrupt and isochronous transfers).  These place some
90 and prevent use of polling intervals of less than one frame.
99     # modprobe ehci-hcd
103     # rmmod ehci-hcd
106 "ohci-hcd"  or "uhci-hcd".  In case of any trouble with the EHCI driver,
114 	Log2 of default interrupt delay, in microframes.  The default
127 		usb-storage doing disk I/O; watch the request queues!)
129 		dumps the periodic schedule, used for interrupt
138 but they may want to check for "usb_device->speed == USB_SPEED_HIGH".
140 can't, such as "high bandwidth" periodic (interrupt or ISO) transfers.
167 (isochronous and interrupt) allow the larger packet sizes which let you
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194 default ehci-hcd driver uses the minimum latency, which means that if
196 it completed in less than 250 usec (depending on transfer size).
199 --------------------
201 To get even 20 MByte/sec transfer rates, Linux-USB device drivers will
210 sequence of 128 KB chunks would waste a lot less.
224    Interrupt and ISO transfer performance issues.  Those periodic