the working environment is: hardware platform: Intel Sandy Bridge Fab2 CRB with a VGA monitor connected Linux kernel: linux-2.6.36 In the kernel, we enable the DRM_I915 & DRM_I915_KMS. When boot up, the DRM driver will change the console from text mode to fb mode, but the fb mode console is always shrunk to the 1/4 size of the screen, can't be full screen any more. I run the xrandr, found the DRM driver detect two connected display devices, one is VGA monitor, the other is LVDS panel. But there is only one display device connected to the board, that is VGA monitor. reproduce steps: On linux-2.6.36, enable DRM, DRM_I915 and DRM_I915_KMS boot up the system as normal After the console is changed to fb mode, the screen is shrunk to 1/4 size
This is a long-standing issue for lvds detection -- we haven't found a reliable way to detect lvds, and assume lvds always available on mobile platform. This is fine for most products, but breaks mobile platform CRB. You could workaround this issue with kernel boot option: video=LVDS-1:d
commit 428d2e828c0a68206e5158a42451487601dc9194 Author: Chris Wilson <chris@chris-wilson.co.uk> Date: Thu Sep 23 11:16:49 2010 +0100 drm/i915/lvds: Probe DDC on creation Try to validate the panel's connection by writing to address 0xA0. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=18072 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> This might help but depends upon re-enabling GMBUS.
Assuming this is fixed now, please re-open if not.
commit f3cfcba60fcfdce89f9332dc6c31137309d33c8a Author: Chris Wilson <chris@chris-wilson.co.uk> Date: Thu Feb 9 09:35:53 2012 +0000 drm/i915/lvds: Always use the presence pin for LVDS on PCH ... for pre-PCH we need to add quirk table entries.