From: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date: Fri, 7 Nov 2014 13:18:45 +0000 (+0200)
Subject: drm/i915: Skip .get_backlight() when backlight isn't enabled
X-Git-Tag: omap-for-v3.19/fixes-rc1~80^2~14^2~103
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d72f6c7be9cd26485f88961f6a56fae3d9d17e9;p=pandora-kernel.git

drm/i915: Skip .get_backlight() when backlight isn't enabled

On VLV/CHV when the display is off, we can't read out the current
backlight level from the hardware since we have no pipe to do so.
Currently we end up reading a bigus register due to passing
INVALID_PIPE to VLV_BLC_PWM_CTL().

Skip the entire .get_backlight() call if the backlight isn't enabled
according to backlight.enabled.

This problem can be reproduced simply by reading the backlight device
actual_brightness file while the display is off.

Cc: Jani Nikula <jani.nikula@intel.com>
Suggested-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---

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