Kconfig DRM_USB/DRM_UDL, and select vs. depends, and causing Tegra USB to be disabled

[Guenter Roeck]

On Tue, Sep 04, 2012 at 01:19:12PM -0600, Stephen Warren wrote:
> With respect to the following commits:
> 
> df0b344 drm/usb: select USB_SUPPORT in Kconfig
> 8f057d7 gpu/mfd/usb: Fix USB randconfig problems
> 
> ... which end up with the following in next-20120904:
> 
> config DRM_USB
>         depends on DRM
>         depends on USB_ARCH_HAS_HCD
>         select USB
>         select USB_SUPPORT
> 
> config DRM_UDL
>         depends on DRM && EXPERIMENTAL
>         depends on USB_ARCH_HAS_HCD
>         select DRM_USB
> 
> Surely this is backwards; these should be dependencies, not selects? In
> other words:
> 
> config DRM_USB
>         depends on DRM && USB
> 
> config DRM_UDL
>         depends on DRM && EXPERIMENTAL && USB
>         select DRM_USB
> 
> or perhaps:
> 
> config DRM_USB
>         depends on DRM && USB
> 
> config DRM_UDL
>         depends on DRM && EXPERIMENTAL && DRM_USB
> 
> The problem here is that currently, the dependency logic for USB:
> 
> config USB
> 	depends on USB_ARCH_HAS_HCD
> 
> ... is duplicated into each of DRM_USB and DRM_UDL, thus requiring both
> of those to be edited should the dependencies for USB ever change.
> 
This should be fixed with in https://patchwork.kernel.org/patch/1373371/ (drm:
udl: usb: Fix recursive Kconfig dependency), which should make it into the next
iteration of linux-next.

Guenter