diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/obsolete/dv1394 | 9 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 11 | ||||
| -rw-r--r-- | Documentation/gpio.txt | 31 | ||||
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 9 | ||||
| -rw-r--r-- | Documentation/x86_64/boot-options.txt | 4 |
5 files changed, 48 insertions, 16 deletions
diff --git a/Documentation/ABI/obsolete/dv1394 b/Documentation/ABI/obsolete/dv1394 new file mode 100644 index 00000000000..2ee36864ca1 --- /dev/null +++ b/Documentation/ABI/obsolete/dv1394 @@ -0,0 +1,9 @@ +What: dv1394 (a.k.a. "OHCI-DV I/O support" for FireWire) +Contact: linux1394-devel@lists.sourceforge.net +Description: + New application development should use raw1394 + userspace libraries + instead, notably libiec61883 which is functionally equivalent. + +Users: + ffmpeg/libavformat (used by a variety of media players) + dvgrab v1.x (replaced by dvgrab2 on top of raw1394 and resp. libraries) diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 0bc8b0b2e10..19b4c96b2a4 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -39,17 +39,6 @@ Who: Dan Dennedy <dan@dennedy.org>, Stefan Richter <stefanr@s5r6.in-berlin.de> --------------------------- -What: dv1394 driver (CONFIG_IEEE1394_DV1394) -When: June 2007 -Why: Replaced by raw1394 + userspace libraries, notably libiec61883. This - shift of application support has been indicated on www.linux1394.org - and developers' mailinglists for quite some time. Major applications - have been converted, with the exception of ffmpeg and hence xine. - Piped output of dvgrab2 is a partial equivalent to dv1394. -Who: Dan Dennedy <dan@dennedy.org>, Stefan Richter <stefanr@s5r6.in-berlin.de> - ---------------------------- - What: Video4Linux API 1 ioctls and video_decoder.h from Video devices. When: December 2006 Why: V4L1 AP1 was replaced by V4L2 API. during migration from 2.4 to 2.6 diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 989f1130f4f..f8528db967f 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -27,7 +27,7 @@ The exact capabilities of GPIOs vary between systems. Common options: - Output values are writable (high=1, low=0). Some chips also have options about how that value is driven, so that for example only one value might be driven ... supporting "wire-OR" and similar schemes - for the other value. + for the other value (notably, "open drain" signaling). - Input values are likewise readable (1, 0). Some chips support readback of pins configured as "output", which is very useful in such "wire-OR" @@ -247,6 +247,35 @@ with gpio_get_value(), for example to initialize or update driver state when the IRQ is edge-triggered. +Emulating Open Drain Signals +---------------------------- +Sometimes shared signals need to use "open drain" signaling, where only the +low signal level is actually driven. (That term applies to CMOS transistors; +"open collector" is used for TTL.) A pullup resistor causes the high signal +level. This is sometimes called a "wire-AND"; or more practically, from the +negative logic (low=true) perspective this is a "wire-OR". + +One common example of an open drain signal is a shared active-low IRQ line. +Also, bidirectional data bus signals sometimes use open drain signals. + +Some GPIO controllers directly support open drain outputs; many don't. When +you need open drain signaling but your hardware doesn't directly support it, +there's a common idiom you can use to emulate it with any GPIO pin that can +be used as either an input or an output: + + LOW: gpio_direction_output(gpio, 0) ... this drives the signal + and overrides the pullup. + + HIGH: gpio_direction_input(gpio) ... this turns off the output, + so the pullup (or some other device) controls the signal. + +If you are "driving" the signal high but gpio_get_value(gpio) reports a low +value (after the appropriate rise time passes), you know some other component +is driving the shared signal low. That's not necessarily an error. As one +common example, that's how I2C clocks are stretched: a slave that needs a +slower clock delays the rising edge of SCK, and the I2C master adjusts its +signaling rate accordingly. + What do these conventions omit? =============================== diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index d3aae1f9b4c..702d1d8dd04 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -851,6 +851,15 @@ accept_redirects - BOOLEAN Functional default: enabled if local forwarding is disabled. disabled if local forwarding is enabled. +accept_source_route - INTEGER + Accept source routing (routing extension header). + + > 0: Accept routing header. + = 0: Accept only routing header type 2. + < 0: Do not accept routing header. + + Default: 0 + autoconf - BOOLEAN Autoconfigure addresses using Prefix Information in Router Advertisements. diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt index 625a21db0c2..85f51e5a749 100644 --- a/Documentation/x86_64/boot-options.txt +++ b/Documentation/x86_64/boot-options.txt @@ -293,7 +293,3 @@ Debugging stuck (default) Miscellaneous - - noreplacement Don't replace instructions with more appropriate ones - for the CPU. This may be useful on asymmetric MP systems - where some CPUs have less capabilities than others. |