[U-Boot] [PATCH] mmc: show error message when "mmc dev" command fails

[Stephen Warren]

On 02/10/2016 05:46 AM, Masahiro Yamada wrote:
> Currently, "mmc dev" can silently fail.  In case of failure, tell
> the user about it.

Does it make sense to print this error inside init_mmc_device() instead, 
so that we don't have to add printf()s to all call sites?

I'm not sure the answer to my question is yes; just something to ponder.

Also note that one disadvantage of printing error messages all the time 
is that the distro boot scripts (by default) attempt to probe all 
defined storage devices, so printing errors will make that noisy. 
Perhaps that should be solved by adding a -q option (for "quiet") so 
those scripts can be non-noisy?