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r: 48682
b: refs/heads/master
c: f52fd66
h: refs/heads/master
v: v3
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Len Brown committed Feb 13, 2007
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2 changes: 1 addition & 1 deletion [refs]
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refs/heads/master: 81450b73dde07f473a4a7208b209b4c8b7251d90
refs/heads/master: f52fd66d2ea794010c2d7536cf8e6abed0ac4947
96 changes: 0 additions & 96 deletions trunk/.mailmap

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17 changes: 7 additions & 10 deletions trunk/Documentation/gpio.txt
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Expand Up @@ -78,8 +78,7 @@ Identifying GPIOs
-----------------
GPIOs are identified by unsigned integers in the range 0..MAX_INT. That
reserves "negative" numbers for other purposes like marking signals as
"not available on this board", or indicating faults. Code that doesn't
touch the underlying hardware treats these integers as opaque cookies.
"not available on this board", or indicating faults.

Platforms define how they use those integers, and usually #define symbols
for the GPIO lines so that board-specific setup code directly corresponds
Expand Down Expand Up @@ -140,10 +139,10 @@ issues including wire-OR and output latencies.
The get/set calls have no error returns because "invalid GPIO" should have
been reported earlier in gpio_set_direction(). However, note that not all
platforms can read the value of output pins; those that can't should always
return zero. Also, using these calls for GPIOs that can't safely be accessed
without sleeping (see below) is an error.
return zero. Also, these calls will be ignored for GPIOs that can't safely
be accessed wihtout sleeping (see below).

Platform-specific implementations are encouraged to optimize the two
Platform-specific implementations are encouraged to optimise the two
calls to access the GPIO value in cases where the GPIO number (and for
output, value) are constant. It's normal for them to need only a couple
of instructions in such cases (reading or writing a hardware register),
Expand Down Expand Up @@ -240,8 +239,7 @@ options are part of the IRQ interface, e.g. IRQF_TRIGGER_FALLING, as are
system wakeup capabilities.

Non-error values returned from irq_to_gpio() would most commonly be used
with gpio_get_value(), for example to initialize or update driver state
when the IRQ is edge-triggered.
with gpio_get_value().



Expand All @@ -262,10 +260,9 @@ pullups (or pulldowns) so that the on-chip ones should not be used.
There are other system-specific mechanisms that are not specified here,
like the aforementioned options for input de-glitching and wire-OR output.
Hardware may support reading or writing GPIOs in gangs, but that's usually
configuration dependent: for GPIOs sharing the same bank. (GPIOs are
configuration dependednt: for GPIOs sharing the same bank. (GPIOs are
commonly grouped in banks of 16 or 32, with a given SOC having several such
banks.) Some systems can trigger IRQs from output GPIOs. Code relying on
such mechanisms will necessarily be nonportable.
banks.) Code relying on such mechanisms will necessarily be nonportable.

Dynamic definition of GPIOs is not currently supported; for example, as
a side effect of configuring an add-on board with some GPIO expanders.
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68 changes: 0 additions & 68 deletions trunk/Documentation/hrtimer/timer_stats.txt

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