drm: Add top level Kconfig option for DRM fbdev emulation

Legacy fbdev emulation support via DRM is achieved through KMS FB helpers.
Most modesetting drivers enable provide fbdev emulation by default by
selecting KMS FB helpers. A few provide a separate Kconfig option for the
user to enable or disbale fbdev emulation.

Enabling fbdev emulation is finally a distro-level decision. Having a top
level Kconfig option for fbdev emulation helps by providing a uniform way
to enable/disable fbdev emulation for any modesetting driver. It also lets
us remove unnecessary driver specific Kconfig options that causes bloat.

With a top level Kconfig in place, we can stub out the fb helper functions
when not needed without breaking functionality. Having stub functions also
prevents drivers to require wrapping fb helper function calls with #ifdefs.

DRM_FBDEV_EMULATION defaults to y since many drivers enable fbdev
emulation by default and majority of distributions expect the fbdev
interface in the kernel.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 35a8c0bf360f..06ae5008c5ed 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -47,6 +47,19 @@ config DRM_KMS_FB_HELPER
         help
           FBDEV helpers for KMS drivers.
 
+config DRM_FBDEV_EMULATION
+        bool "Enable legacy fbdev support for your modesetting driver"
+        depends on DRM
+        select DRM_KMS_HELPER
+        select DRM_KMS_FB_HELPER
+        default y
+        help
+          Choose this option if you have a need for the legacy fbdev
+          support. Note that this support also provides the linux console
+          support on top of your modesetting driver.
+
+          If in doubt, say "Y".
+
 config DRM_LOAD_EDID_FIRMWARE
         bool "Allow to specify an EDID data set instead of probing for it"
         depends on DRM_KMS_HELPER