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authorDavid Brownell <david-b@pacbell.net>2007-03-16 17:38:14 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-03-16 22:25:04 -0400
commit28735a7253a6c24364765e80a5428b4a151fccc2 (patch)
tree824c6391341338dac51f92735d37c83de0d1d522 /drivers/spi
parenta836f5856ae46ccb2464ea76031ea05ae967b832 (diff)
[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>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/atmel_spi.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c
index 6fa260d1a9be..66e7bc985797 100644
--- a/drivers/spi/atmel_spi.c
+++ b/drivers/spi/atmel_spi.c
@@ -425,7 +425,7 @@ static int atmel_spi_setup(struct spi_device *spi)
425 if (ret) 425 if (ret)
426 return ret; 426 return ret;
427 spi->controller_state = (void *)npcs_pin; 427 spi->controller_state = (void *)npcs_pin;
428 gpio_direction_output(npcs_pin); 428 gpio_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH));
429 } 429 }
430 430
431 dev_dbg(&spi->dev, 431 dev_dbg(&spi->dev,