Re: [patch 3/4] MMC-over-SPI core updates

[David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>]

On Friday 15 June 2007, Pierre Ossman wrote:
> David Brownell wrote:
> > 
> > I can move it.  I tried expanding it inline there, and thought
> > the result was worse:  (a) duplication, in both MMC and SD code
> > paths; (b) it complicates otherwise-clean logic; (c) you had
> > asked that the core patch be small.
> > 
> > You're quite sure you want those drawbacks ... ?
> > 
> 
> Fairly. The idea when I did the rewrite was that the initial detection (that
> identifies card type) should be fairly clear and shouldn't require you to dig
> around in other areas.

I figured calling mmc_spi_fixup() would be very clear, and
since it's defined right before the routine using it then
digging would be a non-issue.

But if you want uglified code, I suppose I could do that.  ;)


> >> You also need to fix the check further down as SPI doesn't have a bit indicating
> >> if it toggled into ACMD mode.
> > 
> > Right now this is not needed, since the host records that and hands
> > it back in the R1 status mapping.
> > 
> 
> In other words, lying to the core.

I can't see it that way.  It's just a different way of managing
that status than you currently expect.


> Someone looking at that function will get the 
> impression that the system can verify that the card entered app command mode
> even on spi, even though it can't. Don't try to get the round peg into the
> square hole. Change the hole.

So, get rid of all R1_APP_CMD checks in the MMC stack?
That's what I'll do for now.

I count two of them, and they are both superfluous since
they follow successful completion of MMC_APP_CMD.  The
only way that can succeed is if the card supports APP_CMD
and enters that mode...

(The alternative would be to do the superfluous checks
only for non-SPI hosts, but that'd seem pointless.)

- Dave

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