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

[Philipp Tomsich]

+Kever

Max,

> On 14.12.2018, at 09:21, Max Kellermann <max at blarg.de> wrote:
> 
> 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.

Unfortunately this seems less like a side-effect of that change than of the fact
that there’s a variety of RK3399 boards out there that don’t have dedicated 
board-support in U-Boot and the EVB-defaults may be wrong.
The RK3399-EVB board-suupport does not provide any support to either identify
what board it’s on or to allow overriding these device-order.

@Kever: Could you please confirm whether the CONFIG_SYS_MMC_ENV_DEV
is appropriate for the EVB itself or if it should be changed for the EVB’s config
globally?

Thanks,
Philipp.