On Thu, 04 Aug 2016, David Herrmann dh.herrmann@gmail.com wrote:
Hey
On Thu, Aug 4, 2016 at 9:04 AM, Jani Nikula jani.nikula@linux.intel.com wrote:
On Wed, 03 Aug 2016, Noralf Trønnes noralf@tronnes.org wrote:
Hi,
I have changed simpledrm to use drm_simple_kms_helper and now I'm facing this:
drivers/video/fbdev/Kconfig:5:error: recursive dependency detected! For a resolution refer to Documentation/kbuild/kconfig-language.txt
drivers/video/fbdev/Kconfig:5: symbol FB is selected by DRM_KMS_FB_HELPER
drivers/gpu/drm/Kconfig:42: symbol DRM_KMS_FB_HELPER depends on DRM_KMS_HELPER
drivers/gpu/drm/Kconfig:36: symbol DRM_KMS_HELPER is selected by DRM_SIMPLEDRM
drivers/gpu/drm/simpledrm/Kconfig:1: symbol DRM_SIMPLEDRM depends on FB_SIMPLE
drivers/video/fbdev/Kconfig:2428: symbol FB_SIMPLE depends on FB
Using this Kconfig:
config DRM_SIMPLEDRM tristate "Simple firmware framebuffer DRM driver" depends on DRM && (FB_SIMPLE = n) select DRM_KMS_HELPER
Is there a solution to this apart from depending on DRM_KMS_HELPER or removing the FB_SIMPLE dependency?
I think the underlying problem is the overuse of "select" all around. I think people use it for convenience because unsatisfied "depends" hides a menu option in menuconfig while "select" does not, and it's sometimes hard to find all the dependencies of an option just to *show* it in menuconfig.
I don't know what the exact cause here is, but having hunted these down before, it's often a rabbit hole where you end up having to change a ton of config options to make it robust, and those changes get rejected because the menuconfig convenience is lost, and I've given up. :/
Would be great to have a menuconfig feature to recursively enable and option and all dependencies. Perhaps we could then be more strict about using "select" for stuff with dependencies.
As a workaround, just drop the FB_SIMPLE dependency. It was really just meant as a safety net in my original code. Nothing bad happens if both are enabled. The first to be loaded wins, the other one will very likely print a confusing error message and exit.
Thanks David, and sorry about derailing into a non-helpful rant about kconfig. :/
BR, Jani.