From 2e7eeeb59a92d09144fdb7d2dc1af77a10a7945b Mon Sep 17 00:00:00 2001 From: Jani Nikula Date: Mon, 9 Jun 2014 18:24:34 +0300 Subject: [PATCH] drm/i915: set backlight duty cycle after backlight enable for gen4 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 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 Cc: Stable # 3.14+ Acked-by: Daniel Vetter Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/intel_panel.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index 5e6c888b492886..38a98570d10c86 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -798,9 +798,6 @@ static void i965_enable_backlight(struct intel_connector *connector) 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; @@ -809,6 +806,8 @@ static void i965_enable_backlight(struct intel_connector *connector) 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)