[U-Boot] [PATCH] evb_rk3399: revert CONFIG_SYS_MMC_ENV_DEV to 0

[Max Kellermann]

On 2018/12/13 22:59, Philipp Tomsich <philipp.tomsich at theobroma-systems.com> wrote:
> On 04.12.2018, at 12:00, Max Kellermann <max.kellermann at gmail.com> wrote:
> > 
> > This was changed to 1 in commit 0717dde057e, but a few months later,
> > commit 5f9411af37b swapped the order of eMMC and SD card by assigning
> > indexed aliases to `&sdhci` and `&sdmmc`.
> 
> If this is a straight revert, I’d appreciate it if the was marked as such by
> creating the commit using a 'git revert’ and then adding additional background
> to explain why the revert was done.

Technically, it is a straight revert, but I replaced git's boilerplate
text with a descriptive commit message, without omitting any
information from the boilerplate.  If you prefer to leave the full
boilerplate text in, I can re-add it and resend the patch.

However, semantically, it is not a revert, because it does not revert
the semantic effect of commit 0717dde057e; quite opposite, it restores
the effect of commit 0717dde057e after it was broken by commit
5f9411af37b.

> However, we have a bigger issue here: the original commit has been in the
> tree since 2016 and I am reluctant to change such fundamental naming without
> a rationale.  This is particularily in knowledge of the on-list discussion that we’ve
> had with Kever recently regarding his request to change the search order for booting.

The naming was (accidently?) changed in commit 5f9411af37b, which
effectively undid the effect of commit 0717dde057e, and my patch only
repairs that.

> Could you explain why you think that this should be changed?

The goal of commit 0717dde057e was to boot from eMMC by default, and
at the time, eMMC was "mmc1".  Later, commit 5f9411af37b swapped the
order of "mmc", making eMMC="mmc0".  This broke commit 0717dde057e.

This is how it looks like on my AIO-3399J:

 => mmc list
 dwmmc at fe320000: 1
 sdhci at fe330000: 0 (eMMC)

As you see, CONFIG_SYS_MMC_ENV_DEV=1 will boot from SD card, not from
eMMC.

I submitted the patch because it looked like the side effect of commit
5f9411af37b was an accident, so I attempted fixed it.

Max