[Intel-gfx] [PATCH] drm/i915: tell the user if both KMS and UMS are disabled

[Jani Nikula]

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 e147accbd19f55489dabdcc4dc3551cc3e3f2553
Author: Jani Nikula <jani.nikula at 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 b30324adaf8d2e5950a602bde63030d15a61826f
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Wed Nov 13 22:11:25 2013 +0100

    drm/i915: Deprecated UMS support

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 8949fd26b0ea..f0f690776d45 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1584,6 +1584,8 @@ static int __init i915_init(void)
 	if (!(driver.driver_features & DRIVER_MODESET)) {
 		driver.get_vblank_timestamp = NULL;
 #ifndef CONFIG_DRM_I915_UMS
+		DRM_INFO("Kernel modesetting (KMS) and userspace modesetting (UMS) disabled\n");
+		DRM_INFO("See CONFIG_DRM_I915_UMS, CONFIG_DRM_I915_KMS, nomodeset, and i915.modeset parameters\n");
 		/* Silently fail loading to not upset userspace. */
 		return 0;
 #endif
-- 
1.9.1