linuxppc-dev.lists.ozlabs.org archive mirror
 help / color / mirror / Atom feed
From: Michael Barkowski <michaelbarkowski@ruggedcom.com>
To: linuxppc-dev@ozlabs.org
Cc: Timur Tabi <timur@freescale.com>
Subject: [PATCH] qe_lib: Set gpio data before changing the direction to output
Date: Tue, 18 Aug 2009 16:59:58 -0400	[thread overview]
Message-ID: <4A8B164E.6030704@ruggedcom.com> (raw)

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

             reply	other threads:[~2009-08-18 21:00 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-18 20:59 Michael Barkowski [this message]
     [not found] ` <20090818210805.GA1725@oksana.dev.rtsoft.ru>
2009-08-18 21:20   ` [PATCH v2] qe_lib: Set gpio data before changing the direction to output 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4A8B164E.6030704@ruggedcom.com \
    --to=michaelbarkowski@ruggedcom.com \
    --cc=linuxppc-dev@ozlabs.org \
    --cc=timur@freescale.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).