diff options
| author | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-06-18 18:05:38 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-20 14:28:36 +0200 |
| commit | ecefae6db042283bf88ef3777f2381b18df8ed46 (patch) | |
| tree | 5177129d720add73008eeadd6581fab7c27f5233 /Documentation/usb/ohci.rst | |
| parent | 743344a952fcebee9ca4d783807cf1f03f933baf (diff) | |
docs: usb: rename files to .rst and add them to drivers-api
While there are a mix of things here, most of the stuff
were written from Kernel developer's PoV. So, add them to
the driver-api book.
A follow up for this patch would be to move documents from
there that are specific to sysadmins, adding them to the
admin-guide.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Johan Hovold <johan@kernel.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/usb/ohci.rst')
| -rw-r--r-- | Documentation/usb/ohci.rst | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/Documentation/usb/ohci.rst b/Documentation/usb/ohci.rst new file mode 100644 index 000000000000..bb3c49719e6b --- /dev/null +++ b/Documentation/usb/ohci.rst @@ -0,0 +1,35 @@ +==== +OHCI +==== + +23-Aug-2002 + +The "ohci-hcd" driver is a USB Host Controller Driver (HCD) that is derived +from the "usb-ohci" driver from the 2.4 kernel series. The "usb-ohci" code +was written primarily by Roman Weissgaerber <weissg@vienna.at> but with +contributions from many others (read its copyright/licencing header). + +It supports the "Open Host Controller Interface" (OHCI), which standardizes +hardware register protocols used to talk to USB 1.1 host controllers. As +compared to the earlier "Universal Host Controller Interface" (UHCI) from +Intel, it pushes more intelligence into the hardware. USB 1.1 controllers +from vendors other than Intel and VIA generally use OHCI. + +Changes since the 2.4 kernel include + + - improved robustness; bugfixes; and less overhead + - supports the updated and simplified usbcore APIs + - interrupt transfers can be larger, and can be queued + - less code, by using the upper level "hcd" framework + - supports some non-PCI implementations of OHCI + - ... more + +The "ohci-hcd" driver handles all USB 1.1 transfer types. Transfers of all +types can be queued. That was also true in "usb-ohci", except for interrupt +transfers. Previously, using periods of one frame would risk data loss due +to overhead in IRQ processing. When interrupt transfers are queued, those +risks can be minimized by making sure the hardware always has transfers to +work on while the OS is getting around to the relevant IRQ processing. + +- David Brownell + <dbrownell@users.sourceforge.net> |