Re: [PATCH] mxs-mmc: fix clock rate setting

Wolfram Sang
2011-07-03T10:31:31Z

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On Sun, Jul 03, 2011 at 05:28:52PM +0800, Shawn Guo wrote:
> On Sat, Jul 02, 2011 at 03:12:25PM +0200, Wolfram Sang wrote:
> > On Fri, Jul 01, 2011 at 11:46:29PM +0800, Shawn Guo wrote:
> > > On Fri, Jul 01, 2011 at 04:44:09PM +0200, Wolfram Sang wrote:
> > > > Hi,
> > > >
> > > > On Fri, Jul 01, 2011 at 03:26:39PM +0200, Koen Beel wrote:
> > > > > I send the patch as attachment for now.
> > > >
> > > > Fine with me in this case...
> > > >
> > > > > But I'll have to look into another way of doing this. Corporate mail
> > > > > system is adding stupid disclaimers, gmail web ui is not working ok
> > > > > and corporate firewalls avoid using a different smtp server...
> > > >
> > > > Good luck with that!
> > > >
> > > > About the patch itself: I didn't verify the formulas, but it does solve one
> > > > special problem here. Thanks a lot! So:
> > > >
> > > > Tested-by: Wolfram Sang <w.sang@pengutronix.de>
> > > >
> > > > @chris: If Shawn also likes the patch, I think this is a stable candidate.
> > > >
> > > Thanks for the fixing, Koen.
> > >
> > > Acked-by: Shawn Guo <shawn.guo@freescale.com>
> >
> > Well, maybe not. My colleague complained and I think he is right that we are
> > mapping div2 from the range 0 to 256 (inclusive!) to an 8-bit range. This must
> > be wrong for one value per se.
> >
> If you look at the context of the patch, you will find it's 'div2 - 1'
> than 'div2' gets written into register.

Exactly. The '- 1' is why Koen changed the upper limit from < 256 to <= 256.
The lower limit fix is currently 'if (div2 == 0) div2 == 1', which is a 2:1
mapping. Not good, or?

--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |

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