[PATCH] drm/radeon: Add build directory to include path

[Christian König]

Am 14.04.22 um 09:37 schrieb Michel Dänzer:
> On 2022-04-14 08:24, Christian König wrote:
>> Am 13.04.22 um 18:14 schrieb Michel Dänzer:
>>> From: Michel Dänzer <mdaenzer at redhat.com>
>>>
>>> Fixes compile errors with out-of-tree builds, e.g.
>>>
>>> ../drivers/gpu/drm/radeon/r420.c:38:10: fatal error: r420_reg_safe.h: No such file or directory
>>>      38 | #include "r420_reg_safe.h"
>>>         |          ^~~~~~~~~~~~~~~~~
>>
>> Well stuff like that usually points to a broken build environment.
> Just a separate build directory. Specifically, I'm hitting the errors with
>
>   make -C build-amd64 M=drivers/gpu/drm
>
> Generated headers such as r420_reg_safe.h reside in the build directory, so source files in the source directory can't find them without an explicit search path.

I'm trying to swap back into my brain how all of this used to work, but 
that's a really long time ago that I tried this as well.

> Are you saying that should get added automagically somehow?

Yes, exactly that. I'm like 95% sure that used to work, but I don't know 
why exactly either.

> FWIW, this is pretty common in the kernel according to git grep.

Maybe Alex or somebody else with some more background in the kernel 
Makefiles could jump in and help here.

Christian.