[U-Boot] [PATCH 1/4] mmc: Change board_mmc_getcd() signature.

[Thierry Reding <thierry.reding@avionic-design.de>]

* Marek Vasut wrote:
> > The new API no longer uses the extra cd parameter that was used to store
> > the card presence state. Instead, this information is returned via the
> > function's return value. board_mmc_getcd() returns -1 to indicate that
> > no card-detection mechanism is implemented; 0 indicates that no card is
> > present and 1 is returned if it was detected that a card is present.
> > 
> > Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
> 
> A silly question -- why do we need this change ? Can you explain it in the 
> changelog of V2 too?

It's the first step in implementing card-detection. I discussed this with
Andy and he came up with the idea that board_mmc_getcd() should really have
had the mmc parameter as first argument in the first place instead of the cd
parameter. Furthermore, the cd parameter is used inconsistently in individual
implementations. After some discussion we came to the conclusion that the cd
parameter wasn't required at all and the same information can be represented
in the return value. The whole discussion is in this thread:

	http://lists.denx.de/pipermail/u-boot/2011-November/110180.html

It's not really a necessary change, but it makes board_mmc_getcd() much more
consistent with other MMC-related functions.

Perhaps this last sentence would be a good explanation to put in the v2
commit message?

Thierry
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