Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) ====
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) OHCI
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) ====
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 23-Aug-2002
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) The "ohci-hcd" driver is a USB Host Controller Driver (HCD) that is derived
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) from the "usb-ohci" driver from the 2.4 kernel series.  The "usb-ohci" code
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) was written primarily by Roman Weissgaerber <weissg@vienna.at> but with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) contributions from many others (read its copyright/licencing header).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) It supports the "Open Host Controller Interface" (OHCI), which standardizes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) hardware register protocols used to talk to USB 1.1 host controllers.  As
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) compared to the earlier "Universal Host Controller Interface" (UHCI) from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) Intel, it pushes more intelligence into the hardware.  USB 1.1 controllers
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) from vendors other than Intel and VIA generally use OHCI.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) Changes since the 2.4 kernel include
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 	- improved robustness; bugfixes; and less overhead
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 	- supports the updated and simplified usbcore APIs
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 	- interrupt transfers can be larger, and can be queued
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 	- less code, by using the upper level "hcd" framework
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 	- supports some non-PCI implementations of OHCI
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 	- ... more
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) The "ohci-hcd" driver handles all USB 1.1 transfer types.  Transfers of all
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) types can be queued.  That was also true in "usb-ohci", except for interrupt
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) transfers.  Previously, using periods of one frame would risk data loss due
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) to overhead in IRQ processing.  When interrupt transfers are queued, those
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) risks can be minimized by making sure the hardware always has transfers to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) work on while the OS is getting around to the relevant IRQ processing.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) - David Brownell
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35)   <dbrownell@users.sourceforge.net>