[PATCH] drm/i915/bxt: WA for swapped HPD pins in A stepping

[Sonika Jindal <sonika.jindal@intel.com>]

As per bspec, on BXT A0/A1, sw needs to activate DDIA HPD logic
and interrupts to check the external panel connection.
And remove the redundant comment.

v2: Remove redundant IS_BROXTON check, Add comment about port C not
connected, and rephrase the commit message to include only what we
are doing here (Imre)
v3: Add comment about the WA, move 'hpd' initialization outside for
loop (Siva)
Also, remove few redundant comments from hpd handler (me)

Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c |   46 ++++++++++++++++++++++++++-------------
 1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index a897f68..13cabca 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -88,7 +88,14 @@ static const u32 hpd_status_i915[HPD_NUM_PINS] = {
 	[HPD_PORT_D] = PORTD_HOTPLUG_INT_STATUS
 };
 
-/* BXT hpd list */
+/*
+ * On BXT A0/A1, sw needs to activate DDIA HPD logic and interrupts to check
+ * the external panel connection. Port C is not connected on bxt A0/A1
+ */
+static const u32 hpd_bxt_a0[HPD_NUM_PINS] = {
+	[HPD_PORT_B] = BXT_DE_PORT_HP_DDIA
+};
+
 static const u32 hpd_bxt[HPD_NUM_PINS] = {
 	[HPD_PORT_B] = BXT_DE_PORT_HP_DDIB,
 	[HPD_PORT_C] = BXT_DE_PORT_HP_DDIC
@@ -1967,6 +1974,7 @@ static void bxt_hpd_handler(struct drm_device *dev, uint32_t iir_status)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 hp_control, hp_trigger;
 	u32 pin_mask, long_mask;
+	const u32 *hpd;
 
 	/* Get the status */
 	hp_trigger = iir_status & BXT_DE_PORT_HOTPLUG_MASK;
@@ -1981,7 +1989,12 @@ static void bxt_hpd_handler(struct drm_device *dev, uint32_t iir_status)
 	/* Clear sticky bits in hpd status */
 	I915_WRITE(BXT_HOTPLUG_CTL, hp_control);
 
-	pch_get_hpd_pins(&pin_mask, &long_mask, hp_trigger, hp_control, hpd_bxt);
+	if (INTEL_REVID(dev) < BXT_REVID_B0)
+		hpd = hpd_bxt_a0;
+	else
+		hpd = hpd_bxt;
+
+	pch_get_hpd_pins(&pin_mask, &long_mask, hp_trigger, hp_control, hpd);
 	intel_hpd_irq_handler(dev, pin_mask, long_mask);
 }
 
@@ -3021,31 +3034,34 @@ static void bxt_hpd_irq_setup(struct drm_device *dev)
 	struct intel_encoder *intel_encoder;
 	u32 hotplug_port = 0;
 	u32 hotplug_ctrl;
+	const u32 *hpd;
 
-	/* Now, enable HPD */
-	for_each_intel_encoder(dev, intel_encoder) {
+	if (INTEL_REVID(dev) < BXT_REVID_B0)
+		hpd = hpd_bxt_a0;
+	else
+		hpd = hpd_bxt;
+
+	for_each_intel_encoder(dev, intel_encoder)
 		if (dev_priv->hotplug.stats[intel_encoder->hpd_pin].state
 				== HPD_ENABLED)
-			hotplug_port |= hpd_bxt[intel_encoder->hpd_pin];
-	}
+			hotplug_port |= hpd[intel_encoder->hpd_pin];
 
-	/* Mask all HPD control bits */
 	hotplug_ctrl = I915_READ(BXT_HOTPLUG_CTL) & ~BXT_HOTPLUG_CTL_MASK;
 
-	/* Enable requested port in hotplug control */
 	/* TODO: implement (short) HPD support on port A */
-	WARN_ON_ONCE(hotplug_port & BXT_DE_PORT_HP_DDIA);
-	if (hotplug_port & BXT_DE_PORT_HP_DDIB)
-		hotplug_ctrl |= BXT_DDIB_HPD_ENABLE;
-	if (hotplug_port & BXT_DE_PORT_HP_DDIC)
-		hotplug_ctrl |= BXT_DDIC_HPD_ENABLE;
+	if (INTEL_REVID(dev) < BXT_REVID_B0 && (hotplug_port & BXT_DE_PORT_HP_DDIA))
+		hotplug_ctrl |= BXT_DDIA_HPD_ENABLE;
+	else {
+		if (hotplug_port & BXT_DE_PORT_HP_DDIB)
+			hotplug_ctrl |= BXT_DDIB_HPD_ENABLE;
+		if (hotplug_port & BXT_DE_PORT_HP_DDIC)
+			hotplug_ctrl |= BXT_DDIC_HPD_ENABLE;
+	}
 	I915_WRITE(BXT_HOTPLUG_CTL, hotplug_ctrl);
 
-	/* Unmask DDI hotplug in IMR */
 	hotplug_ctrl = I915_READ(GEN8_DE_PORT_IMR) & ~hotplug_port;
 	I915_WRITE(GEN8_DE_PORT_IMR, hotplug_ctrl);
 
-	/* Enable DDI hotplug in IER */
 	hotplug_ctrl = I915_READ(GEN8_DE_PORT_IER) | hotplug_port;
 	I915_WRITE(GEN8_DE_PORT_IER, hotplug_ctrl);
 	POSTING_READ(GEN8_DE_PORT_IER);
-- 
1.7.10.4

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