linux-i2c.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Dongsoo, Nathaniel Kim" <dongsoo.kim-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: ben-Y5A6D6n0/KfQXOPxS62xeg@public.gmane.org,
	박경민 <kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
	민병호 <bhmin-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
	"Dongsoo Kim"
	<dongsoo45.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
	jsgood.yang-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org
Subject: About a suspicious msleep during doxfer in s3c2410 i2c bus driver
Date: Wed, 22 Jul 2009 17:12:17 +0900	[thread overview]
Message-ID: <5e9665e10907220112m1dbf4975icf1511bc4ac3a1bf@mail.gmail.com> (raw)

Hello,

Since I was working on S3C64XX and C1XX, I found something weird on
I2C bus device.
The thing is that when I try to write multiple registers through I2C
bus, it takes much more time for multiple registers to be written than
any other processor's i2c bus device.
I tracked down for which point does it take and finally found out that
following msleep was making a tremendous delay when I try to write
thousands of registers through I2C bus. Please look at this.

481 static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
482                               struct i2c_msg *msgs, int num)
483 {

<snip>

521         /* ensure the stop has been through the bus */
522
523         msleep(1);


With several different target boards using s3c64xx and s5pc1xx, it
went good without that msleep(). And of course it is working great
with multiple i2c device attached as well.
So, I want to ask Ben and anyone else using I2C device about removing
that msleep might be ok or not. In my case, it went ok. Please let me
know your opinion.
Cheers,

Nate

-- 
=
DongSoo, Nathaniel Kim
Engineer
Mobile S/W Platform Lab.
Digital Media & Communications R&D Centre
Samsung Electronics CO., LTD.
e-mail : dongsoo.kim-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
          dongsoo45.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org

             reply	other threads:[~2009-07-22  8:12 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-22  8:12 Dongsoo, Nathaniel Kim [this message]
     [not found] ` <5e9665e10907220112m1dbf4975icf1511bc4ac3a1bf-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2009-07-22 12:43   ` About a suspicious msleep during doxfer in s3c2410 i2c bus driver Mark Brown
     [not found]     ` <20090722124333.GC7622-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2009-07-22 15:58       ` Dongsoo Kim
     [not found]         ` <E724615E-9F06-4406-9852-041261C5DAA6-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2009-07-22 16:06           ` Mark Brown
     [not found]             ` <20090722160639.GB14026-HF5t3jzXg/6ND3a5+9QAFujbO/Zr0HzV@public.gmane.org>
2009-07-30 22:18               ` Ben Dooks
     [not found]                 ` <20090730221841.GG8850-elnMNo+KYs3pIgCt6eIbzw@public.gmane.org>
2009-07-31  0:20                   ` Dongsoo Kim
2009-07-31  8:05                   ` Peter Korsgaard
     [not found]                     ` <878wi5wa4z.fsf-uXGAPMMVk8amE9MCos8gUmSdvHPH+/yF@public.gmane.org>
2009-08-03  8:04                       ` Ben Dooks
2009-07-31 12:32                   ` Mark Brown

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=5e9665e10907220112m1dbf4975icf1511bc4ac3a1bf@mail.gmail.com \
    --to=dongsoo.kim-re5jqeeqqe8avxtiumwx3w@public.gmane.org \
    --cc=ben-Y5A6D6n0/KfQXOPxS62xeg@public.gmane.org \
    --cc=bhmin-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org \
    --cc=dongsoo45.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org \
    --cc=jsgood.yang-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org \
    --cc=kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org \
    --cc=linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    /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).