On Wed, 01 Apr 2015, Gerd Hoffmann kraxel@redhat.com wrote:
After adding virtio-gpu I get this funky kconfig dependency loop.
scripts/kconfig/conf --oldconfig Kconfig drivers/video/fbdev/Kconfig:5:error: recursive dependency detected! drivers/video/fbdev/Kconfig:5: symbol FB is selected by DRM_KMS_FB_HELPER drivers/gpu/drm/Kconfig:34: symbol DRM_KMS_FB_HELPER is selected by DRM_VIRTIO_GPU drivers/gpu/drm/virtio/Kconfig:1: symbol DRM_VIRTIO_GPU depends on VIRTIO drivers/virtio/Kconfig:1: symbol VIRTIO is selected by REMOTEPROC drivers/remoteproc/Kconfig:4: symbol REMOTEPROC is selected by OMAP_REMOTEPROC drivers/remoteproc/Kconfig:12: symbol OMAP_REMOTEPROC depends on OMAP_IOMMU drivers/iommu/Kconfig:141: symbol OMAP_IOMMU is selected by VIDEO_OMAP3 drivers/media/platform/Kconfig:96: symbol VIDEO_OMAP3 depends on VIDEO_V4L2 drivers/media/v4l2-core/Kconfig:6: symbol VIDEO_V4L2 depends on I2C drivers/i2c/Kconfig:7: symbol I2C is selected by FB_DDC drivers/video/fbdev/Kconfig:59: symbol FB_DDC is selected by FB_CYBER2000_DDC drivers/video/fbdev/Kconfig:374: symbol FB_CYBER2000_DDC depends on FB_CYBER2000 drivers/video/fbdev/Kconfig:362: symbol FB_CYBER2000 depends on FB
Making VIDEO_OMAP3 depend on OMAP_IOMMU instead of selecting it breaks the loop, which looks like the best way to handle it to me. I'm open to better suggestions though.
I think part of the problem is that "select" is often used not as documented [1] but rather as "show my config in menuconfig for convenience even if my dependency is not met, and select the dependency even though I know it can screw up the dependency chain".
In light of the documentation, your patch seems to DTRT. (Disclaimer: I don't work with the drivers in question, hence no Reviewed-by.)
In the big picture, it feels like menuconfig needs a way to display items whose dependencies are not met, and a way to recursively enable said items and all their dependencies when told. This would reduce the resistance to sticking with "select" when clearly "depends" is what's meant.
BR, Jani.
[1] Documentation/kbuild/kconfig-language.txt: "In general use select only for non-visible symbols (no prompts anywhere) and for symbols with no dependencies. That will limit the usefulness but on the other hand avoid the illegal configurations all over."
Signed-off-by: Gerd Hoffmann kraxel@redhat.com
drivers/media/platform/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig index d9b872b..fc21734 100644 --- a/drivers/media/platform/Kconfig +++ b/drivers/media/platform/Kconfig @@ -87,8 +87,8 @@ config VIDEO_OMAP3 tristate "OMAP 3 Camera support" depends on VIDEO_V4L2 && I2C && VIDEO_V4L2_SUBDEV_API && ARCH_OMAP3 depends on HAS_DMA
- depends on OMAP_IOMMU select ARM_DMA_USE_IOMMU
- select OMAP_IOMMU select VIDEOBUF2_DMA_CONTIG ---help--- Driver for an OMAP 3 camera controller.
-- 1.8.3.1
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