| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.15 043/122] drm/i915: set backlight duty cycle after backlight enable for gen4 | Date | Mon, 7 Jul 2014 16:56:45 -0700 |
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3.15-stable review patch. If anyone has any objections, please let me know.
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From: Jani Nikula <jani.nikula@intel.com>
commit 2e7eeeb59a92d09144fdb7d2dc1af77a10a7945b upstream.
For reasons I can't claim to fully understand gen4 seems to require backlight duty cycle setting after the backlight has been enabled, or else black screen follows. I don't have documentation for the correct sequence on gen4 either. Confirmed on Dell Latitude D630 and MacBook4,1.
This fixes a regression introduced by commit b35684b8fa94e04f55fd38bf672b737741d2f9e2 Author: Jani Nikula <jani.nikula@intel.com> Date: Thu Nov 14 12:13:41 2013 +0200
drm/i915: do full backlight setup at enable time
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=75791 Reported-and-tested-by: mcy@lm7.fr Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=79423 Reported-and-tested-by: Marc Milgram <mmilgram@redhat.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/gpu/drm/i915/intel_panel.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -723,9 +723,6 @@ static void i965_enable_backlight(struct ctl = freq << 16; I915_WRITE(BLC_PWM_CTL, ctl); - /* XXX: combine this into above write? */ - intel_panel_actually_set_backlight(connector, panel->backlight.level); - ctl2 = BLM_PIPE(pipe); if (panel->backlight.combination_mode) ctl2 |= BLM_COMBINATION_MODE; @@ -734,6 +731,8 @@ static void i965_enable_backlight(struct I915_WRITE(BLC_PWM_CTL2, ctl2); POSTING_READ(BLC_PWM_CTL2); I915_WRITE(BLC_PWM_CTL2, ctl2 | BLM_PWM_ENABLE); + + intel_panel_actually_set_backlight(connector, panel->backlight.level); } static void vlv_enable_backlight(struct intel_connector *connector)
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