[U-Boot] [U-Boot, v2] env: mmc/fat/ext4: make sure that the MMC sub-system is initialized before using it

[Wolfgang Denk <wd@denx.de>]

Dear Tom Rini,

In message <20180224215325.GQ4311@bill-the-cat> you wrote:
> 
> > Why do you ignore this NAK, and why do you add this patch so late in
> > the release cycle anyway?
> 
> Sorry, didn't v2 address your concerns?  We don't initialize the device
> because maybe we'll have env there, we initalize mmc because we need to
> check that it is there.  Thanks!

No, it does not.  As is, we initialize MMC in the EXT4 code (in
env_ext4_load()). If we go that route, we would have to add similar
init calls to all other file systemn load routines as well.

This does not make sense to me.  This pollutes the code with
unrelated things - file system code should not depend on any
underlaying driver suport.  It increases code size, makes the code
harder to maintain (if you need to change this, there is good
chances to forget the same change in other file systems), and there
is a good chance that in the end you will initialzie MMC even if you
don't use it.

We should keep the code clean and orthogonal.  Driver init code has
no place in file system code.

If needed, the drivers have to make sure to auto--initialize on
first access.

I hold my NAK on this patch.  It is the wrong thing to do.

Best regards,

Wolfgang Denk

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