On Sat 2010-01-02 10:11:10, Ben Nizette wrote:
>
> A good few months ago, commit
>
> commit 8dfd0374be84793360db7fff2e635d2cd3bbcb21
> Author: Sascha Hauer <[email protected]>
> Date: Thu Apr 9 08:32:02 2009 +0200
>
> MMC core: limit minimum initialization frequency to 400kHz
>
> broke a few setups with cards which don't quite adhere to the MMC spec -
> 400kHz is just too fast for them. In my testing, all of the cards which fail
> at 400kHz are OK by about 350Khz but this patch drops the floor to 300 to be
> on the safe side.
>
> Dropping the floor also means that the warning will trigger on some valid
> setups, albeit ones which won't run particularly crappy cards. This patch
> then slightly softens the language of said warning to make it clear it isn't
> always a problem.
>
> V1 of this patch dropped the floor all the way to 50kHz on the basis that it
> was only for a few 100 bytes so that very low speed shouldn't matter. After
> some discussion [1] the consensus was that 50 was too slow after all so this
> patch is a bit more sensible.
>
(please wrap).
> @@ -891,12 +891,12 @@ static void mmc_power_up(struct mmc_host *host)
> */
> mmc_delay(10);
>
> - if (host->f_min > 400000) {
> - pr_warning("%s: Minimum clock frequency too high for "
> + if (host->f_min > 300000) {
> + pr_warning("%s: Minimum clock frequency may be too high for "
> "identification mode\n", mmc_hostname(host));
> host->ios.clock = host->f_min;
> } else
> - host->ios.clock = 400000;
> + host->ios.clock = 300000;
>
> host->ios.power_mode = MMC_POWER_ON;
> mmc_set_ios(host);
Machine with minimum clock of 1MHz is clearly broken, yet you issue
"soft" warning.
What about:
if (f_min > 400k)
print existing warning
else if (f_min > 300k)
print warning 'if your card does not work, its broken, but
your host is unhelpful'
clock = f_min
if (clock < 3o0)
clock = 300
?
Pavel
--
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http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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