[PATCH] drm/tegra: Fix Kconfig dependencies

[Thierry Reding]

On Sun, Jan 05, 2014 at 10:22:51AM -0800, Guenter Roeck wrote:
> arm:allmodconfig fails to build with several undefined drm and host1x symbols.
> 
> drivers/gpu/drm/tegra/bus.c:52: undefined reference to `drm_dev_alloc'
> drivers/gpu/drm/tegra/bus.c:56: undefined reference to `drm_dev_register'
> drivers/gpu/drm/tegra/bus.c:67: undefined reference to `drm_dev_free'
> drivers/gpu/drm/tegra/bus.c:75: undefined reference to `drm_put_dev'
> drivers/gpu/drm/tegra/drm.c:445: undefined reference to `host1x_syncpt_get_base'
> drivers/gpu/drm/tegra/drm.c:449: undefined reference to `host1x_syncpt_base_id'
> 
> and so on.
> 
> This is caused by DRM=m but DRM_TEGRA=y. DRM_TEGRA is bool while DRM is
> tristate. DRM_TEGRA can not be set to tristate because it depends on unexported
> host1x symbols (and possibly others). Fix by updating DRM_TEGRA dependency.
> 
> Also, the DRM_TEGRA help text states that it can be built as module.
> Remove that text since it is not (or no longer) correct.
> 
> Signed-off-by: Guenter Roeck <linux at roeck-us.net>
> ---
>  drivers/gpu/drm/tegra/Kconfig |    5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)

Hi Guenter,

I think this should be fixed in latest next, where it is now possible to
build the Tegra DRM driver as a module. All needed host1x symbols are
exported as well.

One thing that strikes me as odd, though, is that I've always thought
Kconfig would warn if a symbol selected as =y depended on a symbol
selected as =m, precisely because of what you describe above. menuconfig
complains about it pretty loudly as well.

Oh, but I see that if I change DRM_TEGRA back to be bool, then Kconfig
doesn't complain anymore, even if DRM_TEGRA=y and DRM=m. Should that
perhaps be considered a bug?

Thierry
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