[Intel-gfx] [PATCH 1/2] drm/i915: fix the SDE irq dmesg warnings properly

[Jani Nikula]

We had the "The master control interrupt lied (SDE)!" check and error
message in place for a long time without any problems, until

commit aaf5ec2e51ab1d9c5e962b4728a1107ed3ff7a3e
Author: Sonika Jindal <sonika.jindal at intel.com>
Date:   Wed Jul 8 17:07:47 2015 +0530

    drm/i915: Handle HPD when it has actually occurred

caused the errors to start happening. This was bisected and reported,
but the error message was silenced in

commit 97e5ed1111dcc5300a0f59a55248cd243937a8ab
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Fri Oct 23 10:56:12 2015 +0200

    drm/i915: shut up gen8+ SDE irq dmesg noise

shooting the messenger while the debugging for why Sonika's commit
triggered the errors was still in progress.

It looks like we need to read and acknowledge the PCH_PORT_HOTPLUG
register even though the hotplug trigger indicates there isn't a hotplug
irq to handle.

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Sonika Jindal <sonika.jindal at intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92084
Fixes: aaf5ec2e51ab ("drm/i915: Handle HPD when it has actually occurred")
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index c8ba94968aaf..982951d3153a 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1825,7 +1825,17 @@ static void ibx_hpd_irq_handler(struct drm_device *dev, u32 hotplug_trigger,
 	u32 dig_hotplug_reg, pin_mask = 0, long_mask = 0;
 
 	dig_hotplug_reg = I915_READ(PCH_PORT_HOTPLUG);
+	if (!hotplug_trigger) {
+		u32 mask = PORTA_HOTPLUG_STATUS_MASK |
+			PORTD_HOTPLUG_STATUS_MASK |
+			PORTC_HOTPLUG_STATUS_MASK |
+			PORTB_HOTPLUG_STATUS_MASK;
+		dig_hotplug_reg &= ~mask;
+	}
+
 	I915_WRITE(PCH_PORT_HOTPLUG, dig_hotplug_reg);
+	if (!hotplug_trigger)
+		return;
 
 	intel_get_hpd_pins(&pin_mask, &long_mask, hotplug_trigger,
 			   dig_hotplug_reg, hpd,
@@ -1840,8 +1850,7 @@ static void ibx_irq_handler(struct drm_device *dev, u32 pch_iir)
 	int pipe;
 	u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK;
 
-	if (hotplug_trigger)
-		ibx_hpd_irq_handler(dev, hotplug_trigger, hpd_ibx);
+	ibx_hpd_irq_handler(dev, hotplug_trigger, hpd_ibx);
 
 	if (pch_iir & SDE_AUDIO_POWER_MASK) {
 		int port = ffs((pch_iir & SDE_AUDIO_POWER_MASK) >>
@@ -1934,8 +1943,7 @@ static void cpt_irq_handler(struct drm_device *dev, u32 pch_iir)
 	int pipe;
 	u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK_CPT;
 
-	if (hotplug_trigger)
-		ibx_hpd_irq_handler(dev, hotplug_trigger, hpd_cpt);
+	ibx_hpd_irq_handler(dev, hotplug_trigger, hpd_cpt);
 
 	if (pch_iir & SDE_AUDIO_POWER_MASK_CPT) {
 		int port = ffs((pch_iir & SDE_AUDIO_POWER_MASK_CPT) >>
-- 
2.1.4