drm/i915: Reinstate GMBUS and AUX interrupts on gen4/g4x

Now that we're not using MSI anymore on gen4 we can start
using GMBUS and AUX interrupts again. These were disabled on
account of them causing the hardware to somehow generate
legacy interrupts even when MSI was enabled.

See commit c12aba5aa0e6 ("drm/i915: stop using GMBUS IRQs on Gen4
chips") and commit 4e6b788c3f23 ("drm/i915: Disable dp aux irq on
g4x") for more details.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170818183705.27850-17-ville.syrjala@linux.intel.com
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_drv.h

@@ -777,7 +777,6 @@ struct intel_csr {
 	func(has_fpga_dbg); \
 	func(has_full_ppgtt); \
 	func(has_full_48bit_ppgtt); \
-	func(has_gmbus_irq); \
 	func(has_gmch_display); \
 	func(has_guc); \
 	func(has_guc_ct); \
@@ -3095,9 +3094,12 @@ intel_info(const struct drm_i915_private *dev_priv)
  * even when in MSI mode. This results in spurious interrupt warnings if the
  * legacy irq no. is shared with another device. The kernel then disables that
  * interrupt source and so prevents the other device from working properly.
+ *
+ * Since we don't enable MSI anymore on gen4, we can always use GMBUS/AUX
+ * interrupts.
  */
-#define HAS_AUX_IRQ(dev_priv)   ((dev_priv)->info.gen >= 5)
-#define HAS_GMBUS_IRQ(dev_priv) ((dev_priv)->info.has_gmbus_irq)
+#define HAS_AUX_IRQ(dev_priv)   true
+#define HAS_GMBUS_IRQ(dev_priv) (INTEL_GEN(dev_priv) >= 4)
 
 /* With the 945 and later, Y tiling got adjusted so that it was 32 128-byte
  * rows, which changed the alignment requirements and fence programming.

drivers/gpu/drm/i915/i915_pci.c

@@ -200,7 +200,6 @@ static const struct intel_device_info intel_gm45_info __initconst = {
 #define GEN5_FEATURES \
 	.gen = 5, .num_pipes = 2, \
 	.has_hotplug = 1, \
-	.has_gmbus_irq = 1, \
 	.ring_mask = RENDER_RING | BSD_RING, \
 	.has_snoop = true, \
 	GEN_DEFAULT_PIPEOFFSETS, \
@@ -225,7 +224,6 @@ static const struct intel_device_info intel_ironlake_m_info __initconst = {
 	.has_llc = 1, \
 	.has_rc6 = 1, \
 	.has_rc6p = 1, \
-	.has_gmbus_irq = 1, \
 	.has_aliasing_ppgtt = 1, \
 	GEN_DEFAULT_PIPEOFFSETS, \
 	CURSOR_OFFSETS
@@ -268,7 +266,6 @@ static const struct intel_device_info intel_sandybridge_m_gt2_info __initconst =
 	.has_llc = 1, \
 	.has_rc6 = 1, \
 	.has_rc6p = 1, \
-	.has_gmbus_irq = 1, \
 	.has_aliasing_ppgtt = 1, \
 	.has_full_ppgtt = 1, \
 	GEN_DEFAULT_PIPEOFFSETS, \
@@ -321,7 +318,6 @@ static const struct intel_device_info intel_valleyview_info __initconst = {
 	.has_psr = 1,
 	.has_runtime_pm = 1,
 	.has_rc6 = 1,
-	.has_gmbus_irq = 1,
 	.has_gmch_display = 1,
 	.has_hotplug = 1,
 	.has_aliasing_ppgtt = 1,
@@ -412,7 +408,6 @@ static const struct intel_device_info intel_cherryview_info __initconst = {
 	.has_runtime_pm = 1,
 	.has_resource_streamer = 1,
 	.has_rc6 = 1,
-	.has_gmbus_irq = 1,
 	.has_logical_ring_contexts = 1,
 	.has_gmch_display = 1,
 	.has_aliasing_ppgtt = 1,
@@ -474,7 +469,6 @@ static const struct intel_device_info intel_skylake_gt4_info __initconst = {
 	.has_resource_streamer = 1, \
 	.has_rc6 = 1, \
 	.has_dp_mst = 1, \
-	.has_gmbus_irq = 1, \
 	.has_logical_ring_contexts = 1, \
 	.has_guc = 1, \
 	.has_aliasing_ppgtt = 1, \