[U-Boot] [PATCH] mmc: Remove return from mmc_init for non SD 2.0 compatible cards.

Yauhen Kharuzhy jekhor at gmail.com
Thu May 7 23:52:48 CEST 2009


On Thu, May 07, 2009 at 03:13:40PM -0500, Andy Fleming wrote:
> On Thu, May 7, 2009 at 5:08 AM, Yauhen Kharuzhy <jekhor at gmail.com> wrote:
> > Cards which are not compatible with SD 2.0 standard, cat return response
> > for CMD8 command, but it will be invalid in terms of SD 2.0. We should
> > accept this case as admissible.
> >
> > Signed-off-by: Yauhen Kharuzhy <jekhor at gmail.com>
> 
> 
> You've got a typo in the description on a key word, "cat".  Is it can't?  can?
I am sorry, yes, it is 'can'.
> 
> I'm not convinced that this patch is valid.  My understanding is that
> if a card receives a command it does not understand, it should not
> respond.  Thus, if it responds with an error, it's an actual error.
> Are you saying that some cards respond to cmd 8 that don't implement
> 2.0?  Because that would not totally surprise me, but would violate
> not just 2.0, but 1.x, as CMD8 is reserved.  MMC cards should also not
> respond to CMD8 at this stage in initialization, as they are in the
> wrong state...
I just to try all my cards with my device, and every card responds to
CMD8. Probably, this is bug in the implementation of the my MMC host driver
(for Ingenic JZ4740 SoC). I compared card initialization procedure with
Linux kernel's one and found that any error is ignored in it and means
that the card is not SD 2.0 compatible.

I will re-check the host controller driver for timeout handling, but it
seems clear.

-- 
Yauhen Kharuzhy		jekhor _at_ gmail.com
			JID: jek at jabber.ru

A: No
Q: Should I quote below my post?


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