[PATCH 1/2] drm/i915/hotplug: Reduce SHPD_FLITER_CNT for ICL and above

[Suraj Kandpal]

Reduce SHPD_CNT to 250us for ICL and above as it lines up
with DP1.4a(Table3-4) spec.

--v2
-Update commit message and comment [Matt]

--v3
-drop condition and use value of 250us for ICL and above [Matt]

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/i915/display/intel_hotplug_irq.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
index 2c4e946d5575..3a105cfd3c90 100644
--- a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
+++ b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
@@ -849,10 +849,11 @@ static void icp_hpd_irq_setup(struct drm_i915_private *dev_priv)
 	enabled_irqs = intel_hpd_enabled_irqs(dev_priv, dev_priv->display.hotplug.pch_hpd);
 	hotplug_irqs = intel_hpd_hotplug_irqs(dev_priv, dev_priv->display.hotplug.pch_hpd);
 
-	if (INTEL_PCH_TYPE(dev_priv) <= PCH_TGP)
-		intel_uncore_write(&dev_priv->uncore, SHPD_FILTER_CNT, SHPD_FILTER_CNT_500_ADJ);
-	else
-		intel_uncore_write(&dev_priv->uncore, SHPD_FILTER_CNT, SHPD_FILTER_CNT_250);
+	/*
+	 * We reduce the value to 250us to be able to detect SHPD when an external display
+	 * is connected. This is also expected of us as stated in DP1.4a Table 3-4.
+	 */
+	intel_uncore_write(&dev_priv->uncore, SHPD_FILTER_CNT, SHPD_FILTER_CNT_250);
 
 	ibx_display_interrupt_update(dev_priv, hotplug_irqs, enabled_irqs);
 
-- 
2.43.2