[Intel-gfx] [PATCH 3/5] drm/i915: Convert OpRegion ASLE irq worker into a tasklet

[Chris Wilson]

Using a tasklet for an irq bottom-half is the preferred form as it
should ensure minimal latency from the irq to execution of the tasklet.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h       |  2 +-
 drivers/gpu/drm/i915/intel_opregion.c | 19 ++++++-------------
 2 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 3a991bfce067..ce7f30cecb1f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -438,7 +438,7 @@ struct intel_opregion {
 	const void *vbt;
 	u32 vbt_size;
 	u32 *lid_state;
-	struct work_struct asle_work;
+	struct tasklet_struct asle_task;
 };
 #define OPREGION_SIZE            (8*1024)
 
diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
index 8347fd8af8e4..727ca017f5b0 100644
--- a/drivers/gpu/drm/i915/intel_opregion.c
+++ b/drivers/gpu/drm/i915/intel_opregion.c
@@ -521,22 +521,15 @@ static u32 asle_isct_state(struct drm_device *dev)
 	return ASLC_ISCT_STATE_FAILED;
 }
 
-static void asle_work(struct work_struct *work)
+static void asle_task(unsigned long data)
 {
-	struct intel_opregion *opregion =
-		container_of(work, struct intel_opregion, asle_work);
-	struct drm_i915_private *dev_priv =
-		container_of(opregion, struct drm_i915_private, opregion);
+	struct drm_i915_private *dev_priv = (struct drm_i915_private *)data;
 	struct drm_device *dev = dev_priv->dev;
 	struct opregion_asle *asle = dev_priv->opregion.asle;
 	u32 aslc_stat = 0;
 	u32 aslc_req;
 
-	if (!asle)
-		return;
-
 	aslc_req = asle->aslc;
-
 	if (!(aslc_req & ASLC_REQ_MSK)) {
 		DRM_DEBUG_DRIVER("No request on ASLC interrupt 0x%08x\n",
 				 aslc_req);
@@ -577,7 +570,7 @@ static void asle_work(struct work_struct *work)
 void intel_opregion_asle_intr(struct drm_i915_private *dev_priv)
 {
 	if (dev_priv->opregion.asle)
-		schedule_work(&dev_priv->opregion.asle_work);
+		tasklet_schedule(&dev_priv->opregion.asle_task);
 }
 
 #define ACPI_EV_DISPLAY_SWITCH (1<<0)
@@ -814,11 +807,11 @@ void intel_opregion_fini(struct drm_device *dev)
 	if (!opregion->header)
 		return;
 
+	tasklet_kill(&dev_priv->opregion.asle_task);
+
 	if (opregion->asle)
 		opregion->asle->ardy = ASLE_ARDY_NOT_READY;
 
-	cancel_work_sync(&dev_priv->opregion.asle_work);
-
 	if (opregion->acpi) {
 		opregion->acpi->drdy = 0;
 
@@ -938,7 +931,7 @@ int intel_opregion_setup(struct drm_device *dev)
 		return -ENOTSUPP;
 	}
 
-	INIT_WORK(&opregion->asle_work, asle_work);
+	tasklet_init(&opregion->asle_task, asle_task, (unsigned long)dev_priv);
 
 	base = memremap(asls, OPREGION_SIZE, MEMREMAP_WB);
 	if (!base)
-- 
2.8.1