drm: Disable vblank interrupt immediately when drm_vblank_offdelay<0

Make drm_vblank_put() disable the vblank interrupt immediately when the
refcount drops to zero and drm_vblank_offdelay<0.

v2: Preserve the current drm_vblank_offdelay==0 'never disable' behaviur

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

4 files changed, 11 insertions, 7 deletions

diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
index 1d3756d3176c..55923d00bd52 100644
--- a/Documentation/DocBook/drm.tmpl
+++ b/Documentation/DocBook/drm.tmpl
@@ -3386,6 +3386,7 @@ void (*disable_vblank) (struct drm_device *dev, int crtc);</synopsis>
       by scheduling a timer. The delay is accessible through the vblankoffdelay
       module parameter or the <varname>drm_vblank_offdelay</varname> global
       variable and expressed in milliseconds. Its default value is 5000 ms.
+      Zero means never disable, and a negative value means disable immediately.
     </para>
     <para>
       When a vertical blanking interrupt occurs drivers only need to call the
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 92bc6b1d9646..db03e16ca817 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -39,7 +39,7 @@
 unsigned int drm_debug = 0;     /* 1 to enable debug output */
 EXPORT_SYMBOL(drm_debug);
 
-unsigned int drm_vblank_offdelay = 5000;    /* Default to 5000 msecs. */
+int drm_vblank_offdelay = 5000;    /* Default to 5000 msecs. */
 
 unsigned int drm_timestamp_precision = 20;  /* Default to 20 usecs. */
 
@@ -53,7 +53,7 @@ MODULE_AUTHOR(CORE_AUTHOR);
 MODULE_DESCRIPTION(CORE_DESC);
 MODULE_LICENSE("GPL and additional rights");
 MODULE_PARM_DESC(debug, "Enable debug output");
-MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs]");
+MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs] (0: never disable, <0: disable immediately)");
 MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]");
 MODULE_PARM_DESC(timestamp_monotonic, "Use monotonic timestamps");
 
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index b2428cb0c64d..99145c4d536b 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -993,10 +993,13 @@ void drm_vblank_put(struct drm_device *dev, int crtc)
         BUG_ON(atomic_read(&vblank->refcount) == 0);
 
         /* Last user schedules interrupt disable */
-        if (atomic_dec_and_test(&vblank->refcount) &&
-            (drm_vblank_offdelay > 0))
-                mod_timer(&vblank->disable_timer,
-                          jiffies + ((drm_vblank_offdelay * HZ)/1000));
+        if (atomic_dec_and_test(&vblank->refcount)) {
+                if (drm_vblank_offdelay < 0)
+                        vblank_disable_fn((unsigned long)vblank);
+                else if (drm_vblank_offdelay > 0)
+                        mod_timer(&vblank->disable_timer,
+                                  jiffies + ((drm_vblank_offdelay * HZ)/1000));
+        }
 }
 EXPORT_SYMBOL(drm_vblank_put);
 
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index a57646382086..24b32d453c60 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1345,7 +1345,7 @@ extern void drm_put_dev(struct drm_device *dev);
 extern void drm_unplug_dev(struct drm_device *dev);
 extern unsigned int drm_debug;
 
-extern unsigned int drm_vblank_offdelay;
+extern int drm_vblank_offdelay;
 extern unsigned int drm_timestamp_precision;
 extern unsigned int drm_timestamp_monotonic;