On Mon, 21 Jun 2010 13:29:21 +0900, Jaehoon Chung <jh80.chung@xxxxxxxxxxx> wrote: > On 2010-06-18 오후 9:42, Matt Fleming wrote: > > On Fri, 18 Jun 2010 13:05:44 +0900, Jaehoon Chung <jh80.chung@xxxxxxxxxxx> wrote: > >> This patch is bug fixed.. > >> I think that host->ios.clock(initial clock) will be set lower than 400KHz. > >> But in this code, if host->f_min is higher than 400KHz, print warning message and set higher than 400KHz. > >> And We use SDHCI_QUIRK_NONSTANDARD_CLOCK..so using get_min_clock function. > >> but didn't effect nothing through used get_min_clock function. > > > > I'm a little confused. What problem are you fixing with this patch? What > > issue are you seeing? SDHCI_QUIRK_NONSTANDARD_CLOCK is only for sdhci. > > If this is the old "my card won't initialise at 400kHz" chestnut I don't > > think a solution has ever been agreed upon. The problem was that while > > some cards won't initialise at 400kHz, some controllers will try to > > initialise at too low a frequency which causes other problems. > > > > Sascha Hauer explains the reason for setting ios.clock to 400kHz here, > > > > http://lkml.org/lkml/2010/1/5/120 > > > > So I think your patch will cause problems. > > > > Which driver are you using? The driver should have set the f_min value > > to be <= 400kHz. Maybe it is a good idea to set the value of ios.clock > > to 400kHz if the driver has set a bogus f_min value, we will at least > > have a fighting chance of initialising the card (though I would say that > > the driver was broken, but at least core.c will print a warning). > > > > when ios.clock is higher than 400KHz, why not change 400KHz?(if 400KHz seemed like good value) > if clock value is higher than 400KHz, i think card can't initialize...maybe I think this part of your patch is OK. > when sdhci controller set f_min value(ie, 300KHz), clock changed 400KHz in core.c. > just this code purpose to print warning message? Well, the purpose of the code is to set the clock to 400kHz if the value of f_min is too low, as having a low value can cause some controllers to break. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
