[Intel-gfx] [PATCH] drm/i915: hangcheck parameter

[Ben Widawsky]

The hangcheck is undesirable when doing shader debugging. The debugger
interacts with the EU, and these may cause the hangcheck to fire at most
unfortunate times.

This provides a way to let the user disable the hangcheck when they want
to do shader debugging.

Not Signed-off-by, for review only
I will be resubmitting this with full series is ready
---
 drivers/gpu/drm/i915/i915_dma.c |   13 +++++++++----
 drivers/gpu/drm/i915/i915_drv.c |    3 +++
 drivers/gpu/drm/i915/i915_drv.h |    1 +
 drivers/gpu/drm/i915/i915_gem.c |   10 +++++++---
 drivers/gpu/drm/i915/i915_irq.c |   16 +++++++++++-----
 5 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 0239e99..b10249a 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -43,6 +43,8 @@
 #include <linux/slab.h>
 #include <acpi/video.h>
 
+extern unsigned int i915_enable_hangcheck;
+
 static void i915_write_hws_pga(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
@@ -2089,9 +2091,11 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	/* Must be done after probing outputs */
 	intel_opregion_init(dev);
 	acpi_video_register();
-
-	setup_timer(&dev_priv->hangcheck_timer, i915_hangcheck_elapsed,
-		    (unsigned long) dev);
+	if (i915_enable_hangcheck) {
+		dev_priv->enable_hangcheck = true;
+		setup_timer(&dev_priv->hangcheck_timer, i915_hangcheck_elapsed,
+			    (unsigned long) dev);
+	}
 
 	spin_lock(&mchdev_lock);
 	i915_mch_dev = dev_priv;
@@ -2169,7 +2173,8 @@ int i915_driver_unload(struct drm_device *dev)
 	}
 
 	/* Free error state after interrupts are fully disabled. */
-	del_timer_sync(&dev_priv->hangcheck_timer);
+	if (dev_priv->enable_hangcheck)
+		del_timer_sync(&dev_priv->hangcheck_timer);
 	cancel_work_sync(&dev_priv->error_work);
 	i915_destroy_error_state(dev);
 
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 0defd42..a38ce4f 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -70,6 +70,9 @@ module_param_named(vbt_sdvo_panel_type, i915_vbt_sdvo_panel_type, int, 0600);
 static bool i915_try_reset = true;
 module_param_named(reset, i915_try_reset, bool, 0600);
 
+unsigned int i915_enable_hangcheck = 1;
+module_param_named(enable_hangcheck, i915_enable_hangcheck, int, 0600);
+
 static struct drm_driver driver;
 extern int intel_agp_enabled;
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8a9fd91..bfced70 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -320,6 +320,7 @@ typedef struct drm_i915_private {
 #define DRM_I915_HANGCHECK_PERIOD 1500 /* in ms */
 	struct timer_list hangcheck_timer;
 	int hangcheck_count;
+	bool enable_hangcheck;
 	uint32_t last_acthd;
 	uint32_t last_instdone;
 	uint32_t last_instdone1;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index cb1f61d..71377b1 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1777,8 +1777,11 @@ i915_add_request(struct intel_ring_buffer *ring,
 	ring->outstanding_lazy_request = false;
 
 	if (!dev_priv->mm.suspended) {
-		mod_timer(&dev_priv->hangcheck_timer,
-			  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+		if (dev_priv->enable_hangcheck) {
+			mod_timer(&dev_priv->hangcheck_timer,
+				  jiffies +
+				  msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+		}
 		if (was_empty)
 			queue_delayed_work(dev_priv->wq,
 					   &dev_priv->mm.retire_work, HZ);
@@ -3813,7 +3816,8 @@ i915_gem_idle(struct drm_device *dev)
 	 * And not confound mm.suspended!
 	 */
 	dev_priv->mm.suspended = 1;
-	del_timer_sync(&dev_priv->hangcheck_timer);
+	if (dev_priv->enable_hangcheck)
+		del_timer_sync(&dev_priv->hangcheck_timer);
 
 	i915_kernel_lost_context(dev);
 	i915_gem_cleanup_ringbuffer(dev);
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index b9fafe3..73b7071 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -362,9 +362,12 @@ static void notify_ring(struct drm_device *dev,
 	ring->irq_seqno = seqno;
 	wake_up_all(&ring->irq_queue);
 
-	dev_priv->hangcheck_count = 0;
-	mod_timer(&dev_priv->hangcheck_timer,
-		  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+	if (dev_priv->enable_hangcheck) {
+		dev_priv->hangcheck_count = 0;
+		mod_timer(&dev_priv->hangcheck_timer,
+			  jiffies +
+			  msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+	}
 }
 
 static void gen6_pm_rps_work(struct work_struct *work)
@@ -1722,8 +1725,11 @@ void i915_hangcheck_elapsed(unsigned long data)
 
 repeat:
 	/* Reset timer case chip hangs without another request being added */
-	mod_timer(&dev_priv->hangcheck_timer,
-		  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+	if (dev_priv->enable_hangcheck) {
+		mod_timer(&dev_priv->hangcheck_timer,
+			  jiffies +
+			  msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+	}
 }
 
 /* drm_dma.h hooks
-- 
1.7.5.2