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[src/trunk]: src/sys/external/bsd/drm2/dist Rework vblank locking. New drm_v...



details:   https://anonhg.NetBSD.org/src/rev/b20e863a31c4
branches:  trunk
changeset: 366297:b20e863a31c4
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Aug 27 14:42:43 2018 +0000

description:
Rework vblank locking.  New drm_vblank_get/put_locked subroutines.

diffstat:

 sys/external/bsd/drm2/dist/drm/drm_irq.c      |  146 ++++++++++++++++++++-----
 sys/external/bsd/drm2/dist/include/drm/drmP.h |    6 +-
 2 files changed, 120 insertions(+), 32 deletions(-)

diffs (289 lines):

diff -r 33250c3d96bf -r b20e863a31c4 sys/external/bsd/drm2/dist/drm/drm_irq.c
--- a/sys/external/bsd/drm2/dist/drm/drm_irq.c  Mon Aug 27 14:42:23 2018 +0000
+++ b/sys/external/bsd/drm2/dist/drm/drm_irq.c  Mon Aug 27 14:42:43 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: drm_irq.c,v 1.12 2018/08/27 07:03:39 riastradh Exp $   */
+/*     $NetBSD: drm_irq.c,v 1.13 2018/08/27 14:42:43 riastradh Exp $   */
 
 /*
  * drm_irq.c IRQ and vblank support
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: drm_irq.c,v 1.12 2018/08/27 07:03:39 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: drm_irq.c,v 1.13 2018/08/27 14:42:43 riastradh Exp $");
 
 #include <drm/drmP.h>
 #include "drm_trace.h"
@@ -62,6 +62,10 @@
 #include <sys/select.h>
 #endif
 
+/*
+ * Lock order: dev->event_lock, then dev->vbl_lock, then dev->vblank_time_lock
+ */
+
 /* Access macro for slots in vblank timestamp ringbuffer. */
 #define vblanktimestamp(dev, pipe, count) \
        ((dev)->vblank[pipe].time[(count) % DRM_VBLANKTIME_RBSIZE])
@@ -144,6 +148,8 @@
        struct timeval t_vblank;
        int count = DRM_TIMESTAMP_MAXRETRIES;
 
+       assert_spin_locked(&dev->vbl_lock);
+
        spin_lock(&dev->vblank_time_lock);
 
        /*
@@ -198,6 +204,8 @@
        int count = DRM_TIMESTAMP_MAXRETRIES;
        int framedur_ns = vblank->framedur_ns;
 
+       assert_spin_locked(&dev->vbl_lock);
+
        /*
         * Interrupts were disabled prior to this call, so deal with counter
         * wrap if needed.
@@ -331,6 +339,8 @@
        struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
        unsigned long irqflags;
 
+       assert_spin_locked(&dev->vbl_lock);
+
        /* Prevent vblank irq processing while disabling vblank irqs,
         * so no updates of timestamps or count can happen after we've
         * disabled. Needed to prevent races in case of delayed irq's.
@@ -358,6 +368,23 @@
        spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
 }
 
+static void
+vblank_disable_locked(struct drm_vblank_crtc *vblank, struct drm_device *dev,
+    unsigned int pipe)
+{
+
+       BUG_ON(vblank != &dev->vblank[pipe]);
+       assert_spin_locked(&dev->vbl_lock);
+
+       if (!dev->vblank_disable_allowed)
+               return;
+
+       if (atomic_read(&vblank->refcount) == 0 && vblank->enabled) {
+               DRM_DEBUG("disabling vblank on crtc %u\n", pipe);
+               vblank_disable_and_save(dev, pipe);
+       }
+}
+
 static void vblank_disable_fn(unsigned long arg)
 {
        struct drm_vblank_crtc *vblank = (void *)arg;
@@ -1269,6 +1296,38 @@
 }
 
 /**
+ * drm_vblank_get_locked - like drm_vblank_get but caller holds lock
+ * @dev: DRM device
+ * @pipe: index of CRTC to own
+ */
+int
+drm_vblank_get_locked(struct drm_device *dev, unsigned int pipe)
+{
+       struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+       int ret = 0;
+
+       assert_spin_locked(&dev->vbl_lock);
+
+       if (!dev->num_crtcs)
+               return -EINVAL;
+
+       if (WARN_ON(pipe >= dev->num_crtcs))
+               return -EINVAL;
+
+       /* Going from 0->1 means we have to enable interrupts again */
+       if (atomic_add_return(1, &vblank->refcount) == 1) {
+               ret = drm_vblank_enable(dev, pipe);
+       } else {
+               if (!vblank->enabled) {
+                       atomic_dec(&vblank->refcount);
+                       ret = -EINVAL;
+               }
+       }
+
+       return ret;
+}
+
+/**
  * drm_vblank_get - get a reference count on vblank events
  * @dev: DRM device
  * @pipe: index of CRTC to own
@@ -1283,26 +1342,11 @@
  */
 int drm_vblank_get(struct drm_device *dev, unsigned int pipe)
 {
-       struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
        unsigned long irqflags;
-       int ret = 0;
-
-       if (!dev->num_crtcs)
-               return -EINVAL;
-
-       if (WARN_ON(pipe >= dev->num_crtcs))
-               return -EINVAL;
+       int ret;
 
        spin_lock_irqsave(&dev->vbl_lock, irqflags);
-       /* Going from 0->1 means we have to enable interrupts again */
-       if (atomic_add_return(1, &vblank->refcount) == 1) {
-               ret = drm_vblank_enable(dev, pipe);
-       } else {
-               if (!vblank->enabled) {
-                       atomic_dec(&vblank->refcount);
-                       ret = -EINVAL;
-               }
-       }
+       ret = drm_vblank_get_locked(dev, pipe);
        spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 
        return ret;
@@ -1310,6 +1354,16 @@
 EXPORT_SYMBOL(drm_vblank_get);
 
 /**
+ * drm_crtc_vblank_get_locked - like drm_crtc_vblank_get but caller holds lock
+ * @crtc: which CRTC to own
+ */
+int
+drm_crtc_vblank_get_locked(struct drm_crtc *crtc)
+{
+       return drm_vblank_get_locked(crtc->dev, drm_crtc_index(crtc));
+}
+
+/**
  * drm_crtc_vblank_get - get a reference count on vblank events
  * @crtc: which CRTC to own
  *
@@ -1328,6 +1382,36 @@
 EXPORT_SYMBOL(drm_crtc_vblank_get);
 
 /**
+ * drm_vblank_put_locked - like drm_vblank_put but caller holds lock
+ * @dev: DRM device
+ * @pipe: index of CRTC to release
+ */
+void
+drm_vblank_put_locked(struct drm_device *dev, unsigned int pipe)
+{
+       struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+
+       assert_spin_locked(&dev->vbl_lock);
+
+       if (WARN_ON(pipe >= dev->num_crtcs))
+               return;
+
+       if (WARN_ON(atomic_read(&vblank->refcount) == 0))
+               return;
+
+       /* Last user schedules interrupt disable */
+       if (atomic_dec_and_test(&vblank->refcount)) {
+               if (drm_vblank_offdelay == 0)
+                       return;
+               else if (drm_vblank_offdelay < 0)
+                       vblank_disable_locked(vblank, dev, pipe);
+               else if (!dev->vblank_disable_immediate)
+                       mod_timer(&vblank->disable_timer,
+                                 jiffies + ((drm_vblank_offdelay * HZ)/1000));
+       }
+}
+
+/**
  * drm_vblank_put - release ownership of vblank events
  * @dev: DRM device
  * @pipe: index of CRTC to release
@@ -1361,6 +1445,16 @@
 EXPORT_SYMBOL(drm_vblank_put);
 
 /**
+ * drm_crtc_vblank_put_locked - like drm_crtc_vblank_put but caller holds lock
+ * @crtc: which counter to give up
+ */
+void
+drm_crtc_vblank_put_locked(struct drm_crtc *crtc)
+{
+       drm_vblank_put_locked(crtc->dev, drm_crtc_index(crtc));
+}
+
+/**
  * drm_crtc_vblank_put - give up ownership of vblank events
  * @crtc: which counter to give up
  *
@@ -1990,9 +2084,6 @@
 {
        struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
        unsigned long irqflags;
-#ifdef __NetBSD__              /* XXX vblank locking */
-       unsigned long irqflags_vbl_lock;
-#endif
 
        if (WARN_ON_ONCE(!dev->num_crtcs))
                return false;
@@ -2001,9 +2092,6 @@
                return false;
 
        spin_lock_irqsave(&dev->event_lock, irqflags);
-#ifdef __NetBSD__              /* XXX vblank locking */
-       spin_lock_irqsave(&dev->vbl_lock, irqflags_vbl_lock);
-#endif
 
        /* Need timestamp lock to prevent concurrent execution with
         * vblank enable/disable, as this would cause inconsistent
@@ -2015,9 +2103,6 @@
        if (!vblank->enabled) {
                spin_unlock(&dev->vblank_time_lock);
                spin_unlock_irqrestore(&dev->event_lock, irqflags);
-#ifdef __NetBSD__              /* XXX vblank locking */
-               spin_unlock_irqrestore(&dev->vbl_lock, irqflags_vbl_lock);
-#endif
                return false;
        }
 
@@ -2026,7 +2111,9 @@
        spin_unlock(&dev->vblank_time_lock);
 
 #ifdef __NetBSD__
+       spin_lock(&dev->vbl_lock);
        DRM_SPIN_WAKEUP_ONE(&vblank->queue, &dev->vbl_lock);
+       spin_unlock(&dev->vbl_lock);
 #else
        wake_up(&vblank->queue);
 #endif
@@ -2043,9 +2130,6 @@
                vblank_disable_fn((unsigned long)vblank);
 
        spin_unlock_irqrestore(&dev->event_lock, irqflags);
-#ifdef __NetBSD__              /* XXX vblank locking */
-       spin_unlock_irqrestore(&dev->vbl_lock, irqflags_vbl_lock);
-#endif
 
        return true;
 }
diff -r 33250c3d96bf -r b20e863a31c4 sys/external/bsd/drm2/dist/include/drm/drmP.h
--- a/sys/external/bsd/drm2/dist/include/drm/drmP.h     Mon Aug 27 14:42:23 2018 +0000
+++ b/sys/external/bsd/drm2/dist/include/drm/drmP.h     Mon Aug 27 14:42:43 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: drmP.h,v 1.25 2018/08/27 13:42:47 riastradh Exp $      */
+/*     $NetBSD: drmP.h,v 1.26 2018/08/27 14:42:43 riastradh Exp $      */
 
 /*
  * Internal Header for the Direct Rendering Manager
@@ -1071,6 +1071,10 @@
 extern void drm_vblank_put(struct drm_device *dev, unsigned int pipe);
 extern int drm_crtc_vblank_get(struct drm_crtc *crtc);
 extern void drm_crtc_vblank_put(struct drm_crtc *crtc);
+extern int drm_vblank_get_locked(struct drm_device *dev, unsigned int pipe);
+extern void drm_vblank_put_locked(struct drm_device *dev, unsigned int pipe);
+extern int drm_crtc_vblank_get_locked(struct drm_crtc *crtc);
+extern void drm_crtc_vblank_put_locked(struct drm_crtc *crtc);
 extern void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe);
 extern void drm_crtc_wait_one_vblank(struct drm_crtc *crtc);
 extern void drm_vblank_off(struct drm_device *dev, unsigned int pipe);



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