On Thu, 15 Mar 2012 10:52:21 +0100, Carsten Emde C.Emde@osadl.org wrote:
Following the documentation of the Legacy Backlight Brightness (LBB) Register in the configuration space of some Intel PCI graphics adapters, setting the LBB register with the value 0x0 causes the backlight to be turned off, and 0xFF causes the backlight to be set to 100% intensity (http://download.intel.com/embedded/processors/Whitepaper/324567.pdf). The Acer Aspire 5734Z, however, turns the backlight off at 0xFF and sets it to maximum intensity at 0. In consequence, the screen of this systems becomes dark at an early boot stage which makes it unusable. The same inversion applies to the BLC_PWM_CTL I915 register. This problem was introduced in kernel version 2.6.38 when the PCI device of this system was first supported by the i915 KMS module.
This patch adds a quirk to invert the sense of the brightness variable in case an Acer Aspire 5734Z is encountered.
Signed-off-by: Carsten Emde C.Emde@osadl.org
That looks a lot better. However, can I ask for another follow-on patch to enable this quirk by a module parameter as well? I would like to make it easier for anyone else hitting this issue to identity the problem and find a temporary solution until their machine is also quirked.
static void intel_init_quirks(struct drm_device *dev) Index: linux-3.3-rc7/drivers/gpu/drm/i915/intel_panel.c =================================================================== --- linux-3.3-rc7.orig/drivers/gpu/drm/i915/intel_panel.c +++ linux-3.3-rc7/drivers/gpu/drm/i915/intel_panel.c @@ -28,6 +28,7 @@
Chris Wilson <chris@chris-wilson.co.uk>*/
+#include <linux/moduleparam.h> #include "intel_drv.h"
That include is now not required. -Chris