[U-Boot] [PATCH RFC 3/4] ARMV7: OMAP: I2C driver: Restructure i2c_write_byte function

[Steve Sakoman <steve@sakoman.com>]

On Wed, 2010-10-20 at 08:08 +0200, Heiko Schocher wrote:
> Hello Steve,
> 
> Steve Sakoman wrote:
> > This patch removes the "magic number" delays and instead
> > monitors state changes in the status register bits.
> > 
> > Signed-off-by: Steve Sakoman <steve.sakoman@linaro.org>
> > ---
> >  drivers/i2c/omap24xx_i2c.c |   76 +++++++++++++++++++++++--------------------
> >  1 files changed, 41 insertions(+), 35 deletions(-)
> 
> After trying this for the omap3_beagle board, I get an
> compiler warning:
> 
> [hs at pollux u-boot]$ ./MAKEALL omap3_beagle
> Configuring for omap3_beagle board...
> omap24xx_i2c.c: In function 'i2c_write_byte':
> omap24xx_i2c.c:221: warning: unused variable 'stat'

Hmm . . . I can swear I fixed that!  Must be getting old :-)

>    text    data     bss     dec     hex filename
>  218103   11412  202384  431899   6971b ./u-boot
> 
> --------------------- SUMMARY ----------------------------
> Boards compiled: 1
> Boards with warnings or errors: 1 ( omap3_beagle )
> ----------------------------------------------------------
> [hs at pollux u-boot]$
> 
> following patch fixes it.
> 
> BTW:
> Just for the record, your patchset works fine and faster
> on the beagle board, for example:
> 
>                  before your  after your
>                  patchset     patchset
> i2c probe        9s           0,4s
> i2c md 48 0 100  17s          1s

I'm glad that you see the same speedups!

What tool do you use to measure the speedups?

> would you post a v2 of this patch, and I add my
> "Tested-by" to it, or is it OK, if I add my fix patch
> to u-boot-i2c master?

I've posted v2 with your "Tested-by" and the warning fix.

If it helps, the patches are in my omap4-next-upstream branch:

http://www.sakoman.com/cgi-bin/gitweb.cgi?p=u-boot.git;a=shortlog;h=refs/heads/omap4-next-upstream

Thanks for testing and for the comments!

Steve

> From 01c6c59014c4174ad4d13944d740d3491d9cf137 Mon Sep 17 00:00:00 2001
> From: Heiko Schocher <hs@denx.de>
> Date: Wed, 20 Oct 2010 07:57:05 +0200
> Subject: [PATCH] ARMV7: OMAP: I2C driver: fix compiler warning
> 
> Signed-off-by: Heiko Schocher <hs@denx.de>
> ---
>  drivers/i2c/omap24xx_i2c.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/i2c/omap24xx_i2c.c b/drivers/i2c/omap24xx_i2c.c
> index eb153fb..a72d1a1 100644
> --- a/drivers/i2c/omap24xx_i2c.c
> +++ b/drivers/i2c/omap24xx_i2c.c
> @@ -218,7 +218,7 @@ read_exit:
>  static int i2c_write_byte (u8 devaddr, u8 regoffset, u8 value)
>  {
>  	int i2c_error = 0;
> -	u16 status, stat;
> +	u16 status;
> 
>  	/* wait until bus not busy */
>  	wait_for_bb ();
> 
> bye,
> Heiko