[PATCH 2/3][SRU][U] drm/i915: Don't request GMBUS to generate irqs when called while irqs are off

[Koba Ko]

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

BugLink: https://bugs.launchpad.net/bugs/1949321 

We will need to do some i2c poking from the encoder->shutdown() hook.
Currently that gets called after irqs have been turned off. We still
poll the gmbus status bits even if the interrupt never arrives so
things will work just fine. But seems like asking gmbus to generate
interrupts we will never see is a bit pointless, so don't.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211029191802.18448-1-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
(cherry picked from commit fa2a6c5b9cfb0dfbd1b811b154a036df1017ce66
linux-next)
Signed-off-by: Koba Ko <koba.ko at canonical.com>
---
 drivers/gpu/drm/i915/display/intel_gmbus.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_gmbus.c b/drivers/gpu/drm/i915/display/intel_gmbus.c
index ceb1bf8a8c3c..3b8b84177085 100644
--- a/drivers/gpu/drm/i915/display/intel_gmbus.c
+++ b/drivers/gpu/drm/i915/display/intel_gmbus.c
@@ -334,6 +334,15 @@ intel_gpio_setup(struct intel_gmbus *bus, unsigned int pin)
 	algo->data = bus;
 }
 
+static bool has_gmbus_irq(struct drm_i915_private *i915)
+{
+	/*
+	 * encoder->shutdown() may want to use GMBUS
+	 * after irqs have already been disabled.
+	 */
+	return HAS_GMBUS_IRQ(i915) && intel_irqs_enabled(i915);
+}
+
 static int gmbus_wait(struct drm_i915_private *dev_priv, u32 status, u32 irq_en)
 {
 	DEFINE_WAIT(wait);
@@ -344,7 +353,7 @@ static int gmbus_wait(struct drm_i915_private *dev_priv, u32 status, u32 irq_en)
 	 * we also need to check for NAKs besides the hw ready/idle signal, we
 	 * need to wake up periodically and check that ourselves.
 	 */
-	if (!HAS_GMBUS_IRQ(dev_priv))
+	if (!has_gmbus_irq(dev_priv))
 		irq_en = 0;
 
 	add_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
@@ -375,7 +384,7 @@ gmbus_wait_idle(struct drm_i915_private *dev_priv)
 
 	/* Important: The hw handles only the first bit, so set only one! */
 	irq_enable = 0;
-	if (HAS_GMBUS_IRQ(dev_priv))
+	if (has_gmbus_irq(dev_priv))
 		irq_enable = GMBUS_IDLE_EN;
 
 	add_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
-- 
2.25.1