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* [PATCH] qe_lib: Set gpio data before changing the direction to output
@ 2009-08-18 20:59 Michael Barkowski
       [not found] ` <20090818210805.GA1725@oksana.dev.rtsoft.ru>
       [not found] ` <4A8B183D.2030202@freescale.com>
  0 siblings, 2 replies; 9+ messages in thread
From: Michael Barkowski @ 2009-08-18 20:59 UTC (permalink / raw)
  To: linuxppc-dev; +Cc: Timur Tabi

This avoids having a short glitch if the desired initial value is not
the same as what was previously in the data register.

Signed-off-by: Michael Barkowski <michaelbarkowski@ruggedcom.com>
---
I can't think of a reason not to do this.  The data register has no
effect except when the pin is configured as an output, right?

Please enlighten me if this is not correct. The behaviour I see gels
with my thinking, but there may be a case I haven't thought of.

 arch/powerpc/sysdev/qe_lib/gpio.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/sysdev/qe_lib/gpio.c b/arch/powerpc/sysdev/qe_lib/gpio.c
index 3485288..e7bf136 100644
--- a/arch/powerpc/sysdev/qe_lib/gpio.c
+++ b/arch/powerpc/sysdev/qe_lib/gpio.c
@@ -107,12 +107,11 @@ static int qe_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
 
 	spin_lock_irqsave(&qe_gc->lock, flags);
 
+	qe_gpio_set(gc, gpio, val);
 	__par_io_config_pin(mm_gc->regs, gpio, QE_PIO_DIR_OUT, 0, 0, 0);
 
 	spin_unlock_irqrestore(&qe_gc->lock, flags);
 
-	qe_gpio_set(gc, gpio, val);
-
 	return 0;
 }
 
-- 
1.6.3.3

^ permalink raw reply related	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2009-08-25 14:45 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-08-18 20:59 [PATCH] qe_lib: Set gpio data before changing the direction to output Michael Barkowski
     [not found] ` <20090818210805.GA1725@oksana.dev.rtsoft.ru>
2009-08-18 21:20   ` [PATCH v2] " Michael Barkowski
2009-08-18 21:33     ` Anton Vorontsov
2009-08-18 22:33       ` Timur Tabi
2009-08-18 22:56         ` Anton Vorontsov
2009-08-19 13:30           ` Michael Barkowski
2009-08-19 13:32             ` Anton Vorontsov
2009-08-25 14:44     ` Kumar Gala
     [not found] ` <4A8B183D.2030202@freescale.com>
2009-08-18 21:23   ` [PATCH] " Michael Barkowski

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