[PATCH] board: tbs2910: Add support for generic distro configuration

[Denis 'GNUtoo' Carikli]

On Sat, 25 Jan 2020 20:52:36 +0100
Soeren Moch <smoch at web.de> wrote:

> Hi Denis,
Hi,

> thanks for your patch. In general I think it could be a good idea to
> support distroboot on this board, especially if we can maintain
> compatibility with the existing boot procedure. However, since this
> board repeatedly has size problems with the u-boot binary, we
> carefully need to check binary size.
I saw that.

I also experienced size issues with the stock tbs2910_defconfig, and
for now I just locally removed support for things that eats up too much
space like PCIe support.

> There in no SPL for tbs2910. So this is not required.
Ahh ok, now I understand. That probably explains the repeated size
issues.

For my patch, I could guard the code addition with some ifdefs for
CONFIG_DISTRO_DEFAULTS if necessary. Note that CONFIG_DISTRO_DEFAULTS is
not set in the tbs2910_defconfig, so if done correctly it should not
make things worse.

In the long run it's probably worth looking into adding SPL support.
For instance the Wandboard has it. I'll try to find the time to look
into it but I can't guarantee anything.

As for the rest of the questions:
> Why do you define CONFIG_BOOTCOMMAND here instead of modifying the
> existing one?
> > +#define CONFIG_BOOTCOMMAND \
> > +	"mmc rescan; " \
> > +	"if run bootcmd_up1; then " \
> > +		"run bootcmd_up2; " \
> > +	"else " \
> > +		"run bootcmd_mmc || run distro_bootcmd; " \
> > +	"fi"
> > +  
> Why do you define CONFIG_BOOTCOMMAND here instead of modifying the
> existing one?
I'm a bit confused with it: There seem to be many way to do the same
thing and I'm not sure which one is the best.

Because of that, I just kept it in the code as it was (instead of
moving it to tbs2910_defconfig).

I'm also not sure if it's best to run distro_bootcmd before or
after the bootcmd_up1/bootcmd_up2/bootcmd_mmc commands, which are
probably used to boot some distribution like LibreElec.

Denis.
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