Re: [PATCH v3] mmc: Make ID freq configurable

[Pierre Ossman]

On Sun, 3 Jan 2010 09:23:30 +1100
Ben Nizette <bn@xxxxxxxxxxxxxxx> wrote:

> > 
> > Broken cards seem to be all over the spectrum, so I wouldn't be
> > suprised if you find ones that break if you go too low as well.
> 
> Yea good point, though given there might not even be a One Freq to Rule Them All, how about:
> 
> ---8<---
> 
> From: Ben Nizette <bn@xxxxxxxxxxxxxxx>
> Subject: [PATCH v3] mmc: Make ID freq configurable
> 
> While the SD spec specifies a range of frequencies for the ID phase from 100-400kHz, not all cards play by the rules.  This patch adds a Kconfig option to allow the user to tweak this to their card/host config, though the default of 250kHz should be fine for all spec-abiding cards and most others besides.
> 
> Signed-off-by: Ben Nizette <bn@xxxxxxxxxxxxxxx>
> 

This is not a good solution. We all use the same pool of cards so we
should all be using the same init sequence. If there isn't a single
frequency where all cards will work, then we'll have to make something
more advanced where the kernel will try the init several times with
different clocking.

Rgds
-- 
     -- Pierre Ossman

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