Messages in this thread | | | Date | Thu, 25 Sep 2008 09:05:56 +0200 | From | Pierre Ossman <> | Subject | Re: [PATCH 3/4] atmel-mci: support multiple mmc slots |
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On Wed, 24 Sep 2008 16:35:27 +0200 Haavard Skinnemoen <haavard.skinnemoen@atmel.com> wrote:
> > On AP7000, the clock line is shared. Do I have to run the clock at the > minimum of the two slots' maximum rates, or does it only matter when > the card is being accessed? >
I'd say always. I'd never dare overclock something that's powered, even if we're not currently communicating with it.
Remember to deal with the case of a powered but unclocked card. This will primarily happen during card init, but it could should up later as well if we start implementing aggressive power management.
> > > > (This will also get a bit more painful when/if the core starts > > > > disabling the clock when a card is idle) > > > > > > The atmel-mci driver already stops the clock between requests. > > > > Then I expect a patch to remove that. Fiddling with the clock is > > dangerous and I've seen everything from hung cards to silently broken > > writes when you disable the clock too early after a request. > > Ok. I'll see if I can fix that -- I take it you want a patch for > 2.6.27, then? >
.28 should be fine. It's a pretty uncommon bug.
> > > > > > > > Fall back to polling? > > > > > > Probably, yes. Can I fall back to polling after the host has been > > > registered? > > > > > > > Hmm... no. Not sure how to handle this... > > I'll see if I can figure out a way to do it. I'm not giving it high > priority since it's a fairly obscure error case which shouldn't happen > with properly implemented board code. >
Agreed.
-- -- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org rdesktop, core developer http://www.rdesktop.org
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