From mboxrd@z Thu Jan  1 00:00:00 1970
From: Martin Kelly <mkelly@xevo.com>
Date: Thu, 31 May 2018 12:48:56 -0700
Subject: [U-Boot] [PATCH] sunxi: allow CONFIG_DEFAULT_FDT_FILE override
In-Reply-To: <8378D51C-2DE2-4735-9223-DD270C409BF3@theobroma-systems.com>
References: <20180502004641.13415-1-mkelly@xevo.com>
 <20180517120118.vd6apamndc4i6ux2@flea>
 <09689eb8-9451-9508-319d-23aafba36e3b@xevo.com>
 <13fb068e-2397-a8d4-0272-0749c0316c6f@xevo.com>
 <8378D51C-2DE2-4735-9223-DD270C409BF3@theobroma-systems.com>
Message-ID: <391f7591-308d-1bf6-d724-1513644aca08@xevo.com>
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On 05/31/2018 11:15 AM, klaus.goger at theobroma-systems.com wrote:
> Hi Martin,
> 
>> On 31.05.2018, at 19:49, Martin Kelly <mkelly@xevo.com> wrote:
>>
>> On 05/23/2018 11:34 AM, Martin Kelly wrote:
>>> On 05/17/2018 05:01 AM, Maxime Ripard wrote:
>>>> On Tue, May 01, 2018 at 05:46:41PM -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.
>>>>>
>>>>> Add logic in sunxi-common.h to respect CONFIG_DEFAULT_FDT_FILE, if set,
>>>>> and default to the values it currently uses.
>>>>>
>>>>> Signed-off-by: Martin Kelly <mkelly@xevo.com>
>>>>
>>>> Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
>>>>
>>>> Maxime
>>>>
>>> (ping)
>>
>> (ping again)
>>
>> Can we get this patch merged?
> 
> The else branch will never be selected.
> CONFIG_DEFAULT_FDT_FILE will be set to “” if not set by your defconfig.
> 

Thanks for noticing this; unfortunately you are right. I thought I 
tested this, but it was in the context of a larger build and I missed it.

It looks like we have two options:

(a) Test for empty string in preprocessor language. This is quite ugly 
and has some gotchas but should be doable (e.g. 
https://stackoverflow.com/questions/3781520/how-to-test-if-preprocessor-symbol-is-defined-but-has-no-value).

(b) Always use the value of CONFIG_DEFAULT_FDT_FILE and stop using 
CONFIG_DEFAULT_DEVICE_TREE as a default. In each board file, explicitly 
set CONFIG_DEFAULT_FDT_FILE to its current default. This is what other 
boards are doing.

I favor (b). If others are in favor, I'll submit a patch for it.