drm/i915: tell the user if both KMS and UMS are disabled

If both KMS is disabled (by i915.modeset=0 or nomodeset parameters) and
UMS is disabled (by CONFIG_DRM_I915_UMS=n, the default), the user might
not be aware his setup is not supported. Inform the users (and, by
extension, the poor i915 developers having to read their dmesgs in bug
reports) why their graphics experience might be lacking.

A similar message was added on the UMS path in
commit 07cae84287587e8e1d5aa41fc88798e54c1cb0d0
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Thu Oct 10 15:25:37 2013 +0300

    drm/i915: tell the user KMS is required for gen6+

but it won't be reached if CONFIG_DRM_I915_UMS=n since
commit d0a75147d56123942dfa2ef3fae1b57020c38cfa
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Nov 13 22:11:25 2013 +0100

    drm/i915: Deprecated UMS support

v2: Use DRM_DEBUG_DRIVER.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 481d2a14cdc697de5ac79e3f850994a920d78025..fa7138215b56c786033a99a531254a51285cc304 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1583,6 +1583,7 @@ static int __init i915_init(void)
                driver.get_vblank_timestamp = NULL;
 #ifndef CONFIG_DRM_I915_UMS
                /* Silently fail loading to not upset userspace. */
+               DRM_DEBUG_DRIVER("KMS and UMS disabled.\n");
                return 0;
 #endif
        }