]> err.no Git - linux-2.6/commit
[PATCH] gpio_direction_output() needs an initial value
authorDavid Brownell <david-b@pacbell.net>
Fri, 16 Mar 2007 21:38:14 +0000 (13:38 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Sat, 17 Mar 2007 02:25:04 +0000 (19:25 -0700)
commit28735a7253a6c24364765e80a5428b4a151fccc2
tree824c6391341338dac51f92735d37c83de0d1d522
parenta836f5856ae46ccb2464ea76031ea05ae967b832
[PATCH] gpio_direction_output() needs an initial value

It's been pointed out that output GPIOs should have an initial value, to
avoid signal glitching ...  among other things, it can be some time before
a driver is ready.  This patch corrects that oversight, fixing

 - documentation
 - platforms supporting the GPIO interface
 - users of that call (just one for now, others are pending)

There's only one user of this call for now since most platforms are still
using non-generic GPIO setup code, which in most cases already couples the
initial value with its "set output mode" request.

Note that most platforms are clear about the hardware letting the output
value be set before the pin direction is changed, but the s3c241x docs are
vague on that topic ...  so those chips might not avoid the glitches.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Andrew Victor <andrew@sanpeople.com>
Acked-by: Milan Svoboda <msvoboda@ra.rockwell.com>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/gpio.txt
arch/arm/mach-at91/gpio.c
arch/arm/mach-sa1100/generic.c
arch/avr32/mach-at32ap/pio.c
drivers/spi/atmel_spi.c
include/asm-arm/arch-at91/gpio.h
include/asm-arm/arch-omap/gpio.h
include/asm-arm/arch-pxa/gpio.h
include/asm-arm/arch-s3c2410/gpio.h
include/asm-arm/arch-sa1100/gpio.h
include/asm-avr32/arch-at32ap/gpio.h