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authorJani Nikula <jani.nikula@intel.com>2014-04-09 10:31:37 +0200
committerJani Nikula <jani.nikula@intel.com>2014-04-11 12:22:57 +0200
commitc675949ec58ca50d5a3ae3c757892f1560f6e896 (patch)
treebc119a7d1877b34d7421ae0da9ef91a9d0e25ecb
parentdrm/i915: check VBT for supported backlight type (diff)
downloadlinux-c675949ec58ca50d5a3ae3c757892f1560f6e896.tar.xz
linux-c675949ec58ca50d5a3ae3c757892f1560f6e896.zip
drm/i915: do not setup backlight if not available according to VBT
Some machines use an external EC for controlling the backlight. Info about this is present in the VBT. Do not setup native backlight control if no PWM backlight is available or supported according to VBT. The acpi_backlight interface appears to work for the EC control. In most cases there has been no harm done, but it looks like there are machines out there that have both an EC and our PWM line connected to the same wire. This, obviously, does not end well. This should fix the regression caused by commit bc0bb9fd1c7810407ab810d204bbaecb255fddde Author: Jani Nikula <jani.nikula@intel.com> Date: Thu Nov 14 12:14:29 2013 +0200 drm/i915: remove QUIRK_NO_PCH_PWM_ENABLE AFAICT the quirk removed by the above commit effectively resulted in i915 not driving the backlight PWM output, thus not messing things up. Additionally this should fix the regression caused by commit fbc9fe1b4f222a7c575e3bd8e9defe59c6190a04 Author: Aaron Lu <aaron.lu@intel.com> Date: Fri Oct 11 21:27:45 2013 +0800 ACPI / video: Do not register backlight if win8 and native interface exists which left some machines without a functioning backlight interface. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76276 Reference: https://bugzilla.kernel.org/show_bug.cgi?id=47941 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=62281 CC: Aaron Lu <aaron.lu@intel.com> CC: Eric Griffith <EGriffith92@gmail.com> CC: Kent Baxley <kent.baxley@canonical.com> Tested-by: Kamal Mostafa <kamal@canonical.com> Tested-by: Martin <bugs@mrvanes.com> Tested-by: jrg.otte@gmail.com Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
-rw-r--r--drivers/gpu/drm/i915/intel_panel.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index cb058408c70e..0eead16aeda7 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1065,6 +1065,11 @@ int intel_panel_setup_backlight(struct drm_connector *connector)
unsigned long flags;
int ret;
+ if (!dev_priv->vbt.backlight.present) {
+ DRM_DEBUG_KMS("native backlight control not available per VBT\n");
+ return 0;
+ }
+
/* set level and max in panel struct */
spin_lock_irqsave(&dev_priv->backlight_lock, flags);
ret = dev_priv->display.setup_backlight(intel_connector);