[U-Boot] [PATCH] sunxi: use CONFIG_DEFAULT_FDT_FILE everywhere

[Martin Kelly]

On 06/01/2018 04:05 AM, Maxime Ripard wrote:
> On Thu, May 31, 2018 at 05:59:16PM -0700, Martin Kelly wrote:
>> Currently, sunxi-common.h ignores CONFIG_DEFAULT_FDT_FILE and assumes
>> the kernel fdtfile and the u-boot devicetree names are the same.
>> Although this is typically the case, sometimes you might want to
>> customize one of these differently, so it's useful to allow them to be
>> different.
>>
>> Fix this to use only CONFIG_DEFAULT_FDT_FILE as other boards do, and set
>> CONFIG_DEFAULT_FDT_FILE in board files to be the same as the current
>> fdtfile= setting.
>>
>> Signed-off-by: Martin Kelly <mkelly at xevo.com>
> 
> I'd really prefer not to do that. There's going to be a long trail of
> defconfig that will be sent at pretty much the same time that are not
> going to have it and that will go unnotice for some time.
> 
> And there's obviously the useless churn in all the defconfig that are
> not in the case where it makes sense to override DEFAULT_FDT_FILE.
> 
> Why not create a Kconfig boolean that allows to select whether or not
> you want DEFAULT_FDT_FILE to be DEFAULT_DEVICE_TREE + .dtb or a custom
> value.
> 
> Maxime
> 

I can see the issues with new defconfigs, but I'm not sure if it will 
really be that bad. If we apply this patch against sunxi master, then 
shouldn't new patches get tested and rebased against it? In that case, 
if they have not set DEFAULT_FDT_FILE, it will default to "", the boards 
won't boot, and the mistake must be fixed prior to merging.

Alternatively if we add the Kconfig boolean, we need to worry about what 
happens when people have DEFAULT_FDT_FILE set already. I guess we would 
need to default the new Kconfig boolean to be custom in order to keep 
those configs from breaking. But if we do that, sunxi will break by 
default (since sunxi configs don't have the value set).

What would you suggest the default value of the new boolean to be?

Personally, though I think it could be a bit painful through the next 
merge window, I think fixing this to operate the same way as the rest of 
the boards is the right long-term decision.

That said, I'll add the boolean if others disagree and we figure out the 
right default value to avoid breaking existing configs.