[Intel-gfx] [PATCH] drm/i915: Enable GSE interrupt on BDW+

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

We've never actually enabled or unmasked the GSE interrupt on BDW+,
even though the interrupt handler was always prepared for it.
Let's enable it and see what happens.

Credit to Mark Kettenis who fixed this in the OpenBSD fork of the
driver. He reports that it fixed the "ACPI _BCM/_BCQ-based
brightness mechanism on a MacBookPro12,1 and a 3rd gen Lenovo X1
Carbon" for them.

References: http://lists.freedesktop.org/archives/intel-gfx/2015-December/081799.html
Reported-by: Mark Kettenis <mark.kettenis at xs4all.nl>
Cc: Mark Kettenis <mark.kettenis at xs4all.nl>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index e88d692583a5..ccdac24039e8 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -3655,6 +3655,7 @@ static void gen8_de_irq_postinstall(struct drm_i915_private *dev_priv)
 	uint32_t de_pipe_enables;
 	u32 de_port_masked = GEN8_AUX_CHANNEL_A;
 	u32 de_port_enables;
+	u32 de_misc_masked = GEN8_DE_MISC_GSE;
 	enum pipe pipe;
 
 	if (INTEL_INFO(dev_priv)->gen >= 9) {
@@ -3690,6 +3691,7 @@ static void gen8_de_irq_postinstall(struct drm_i915_private *dev_priv)
 					  de_pipe_enables);
 
 	GEN5_IRQ_INIT(GEN8_DE_PORT_, ~de_port_masked, de_port_enables);
+	GEN5_IRQ_INIT(GEN8_DE_MISC_, ~de_misc_masked, de_misc_masked);
 }
 
 static int gen8_irq_postinstall(struct drm_device *dev)
-- 
2.4.10