drm/i915: hangcheck disable parameter

Provide a parameter to disable hanghcheck. This is useful mostly for
developers trying to debug known problems, and probably should not be
touched by normal users.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Keith Packard <keithp@keithp.com>

4 files changed, 18 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 609358faaa90..b54f7d9b173a 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);
 
+bool i915_enable_hangcheck = true;
+module_param_named(enable_hangcheck, i915_enable_hangcheck, bool, 0644);
+
 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 01affb63be29..e0f9ca3e5ff8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -994,6 +994,7 @@ extern unsigned int i915_panel_use_ssc;
 extern int i915_vbt_sdvo_panel_type;
 extern unsigned int i915_enable_rc6;
 extern unsigned int i915_enable_fbc;
+extern bool i915_enable_hangcheck;
 
 extern int i915_suspend(struct drm_device *dev, pm_message_t state);
 extern int i915_resume(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 71cc8a353a78..8b670e7ee404 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1779,8 +1779,11 @@ 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 (i915_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);
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index ae2b49969b99..0b0de5239ad5 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -361,10 +361,12 @@ 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 (i915_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)
@@ -1664,6 +1666,9 @@ void i915_hangcheck_elapsed(unsigned long data)
         uint32_t acthd, instdone, instdone1;
         bool err = false;
 
+        if (!i915_enable_hangcheck)
+                return;
+
         /* If all work is done then ACTHD clearly hasn't advanced. */
         if (i915_hangcheck_ring_idle(&dev_priv->ring[RCS], &err) &&
             i915_hangcheck_ring_idle(&dev_priv->ring[VCS], &err) &&