[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,

In message <20180225134810.GU4311@bill-the-cat> you wrote:
> 
> > 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.
> 
> I think you have this a little bit wrong.  But, it's also where we are
> with the DM conversion.  This _is_ the first place we're trying to
> access the MMC.  And it's not in the filesystem code, it's in the
> environment code.

Maybe I was not really clear.  You are right as this is not generic
file system code.  Instead, it is the EXT4 support code for the
environment handling.

The patch adds mmc_initialize() to env_ext4_load(), so whenever we
try to load the environment from an EXT4 file system, it will
initialize the MMC subsystem.

However - what if we want to load the environment from an EXT4 file
system on any other storage device - say, USB, or SATA, or flash?

In all such cases the initialization of MMC would be plain wrong.


And what if we want to load the environment from any other type of
file system - say, cramfs, zfs, etc. - on SDCard or eMMC?  These do
not initialize MMC, so it would fail?

Yes, we have the same crappy code in env/fat.c, but this is the
wrong thing to do, and must be cleaned up there as well.


This is what I meant when I wrote that the file system (interface)
code and the storage device support code are independent of each
other, and code should be kept orthogonal - storage support like MMC
etc. has no place in code dealing with a specific file system type.

I still think my NAK is reasonable.

Best regards,

Wolfgang Denk

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