drm/vbl rework: rework how the drm deals with vblank.

Other Authors: Michel Dänzer <michel@tungstengraphics.com>
mga: Ian Romanick <idr@us.ibm.com>
via: Thomas Hellstrom <thomas-at-tungstengraphics-dot-com>

This re-works the DRM internals to provide a better interface for drivers
to expose vblank on multiple crtcs.

It also includes work done by Michel on making i915 triple buffering and pageflipping work properly.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 325 insertions, 56 deletions

diff --git a/drivers/char/drm/drm_irq.c b/drivers/char/drm/drm_irq.c
index 089c015c01d1..286f9d61e7d5 100644
--- a/drivers/char/drm/drm_irq.c
+++ b/drivers/char/drm/drm_irq.c
@@ -71,6 +71,117 @@ int drm_irq_by_busid(struct drm_device *dev, void *data,
         return 0;
 }
 
+static void vblank_disable_fn(unsigned long arg)
+{
+        struct drm_device *dev = (struct drm_device *)arg;
+        unsigned long irqflags;
+        int i;
+
+        for (i = 0; i < dev->num_crtcs; i++) {
+                spin_lock_irqsave(&dev->vbl_lock, irqflags);
+                if (atomic_read(&dev->vblank_refcount[i]) == 0 &&
+                    dev->vblank_enabled[i]) {
+                        dev->driver->disable_vblank(dev, i);
+                        dev->vblank_enabled[i] = 0;
+                }
+                spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
+        }
+}
+
+static void drm_vblank_cleanup(struct drm_device *dev)
+{
+        /* Bail if the driver didn't call drm_vblank_init() */
+        if (dev->num_crtcs == 0)
+                return;
+
+        del_timer(&dev->vblank_disable_timer);
+
+        vblank_disable_fn((unsigned long)dev);
+
+        drm_free(dev->vbl_queue, sizeof(*dev->vbl_queue) * dev->num_crtcs,
+                 DRM_MEM_DRIVER);
+        drm_free(dev->vbl_sigs, sizeof(*dev->vbl_sigs) * dev->num_crtcs,
+                 DRM_MEM_DRIVER);
+        drm_free(dev->_vblank_count, sizeof(*dev->_vblank_count) *
+                 dev->num_crtcs, DRM_MEM_DRIVER);
+        drm_free(dev->vblank_refcount, sizeof(*dev->vblank_refcount) *
+                 dev->num_crtcs, DRM_MEM_DRIVER);
+        drm_free(dev->vblank_enabled, sizeof(*dev->vblank_enabled) *
+                 dev->num_crtcs, DRM_MEM_DRIVER);
+        drm_free(dev->last_vblank, sizeof(*dev->last_vblank) * dev->num_crtcs,
+                 DRM_MEM_DRIVER);
+        drm_free(dev->vblank_premodeset, sizeof(*dev->vblank_premodeset) *
+                 dev->num_crtcs, DRM_MEM_DRIVER);
+        drm_free(dev->vblank_offset, sizeof(*dev->vblank_offset) * dev->num_crtcs,
+                 DRM_MEM_DRIVER);
+
+        dev->num_crtcs = 0;
+}
+
+int drm_vblank_init(struct drm_device *dev, int num_crtcs)
+{
+        int i, ret = -ENOMEM;
+
+        setup_timer(&dev->vblank_disable_timer, vblank_disable_fn,
+                    (unsigned long)dev);
+        spin_lock_init(&dev->vbl_lock);
+        atomic_set(&dev->vbl_signal_pending, 0);
+        dev->num_crtcs = num_crtcs;
+
+        dev->vbl_queue = drm_alloc(sizeof(wait_queue_head_t) * num_crtcs,
+                                   DRM_MEM_DRIVER);
+        if (!dev->vbl_queue)
+                goto err;
+
+        dev->vbl_sigs = drm_alloc(sizeof(struct list_head) * num_crtcs,
+                                  DRM_MEM_DRIVER);
+        if (!dev->vbl_sigs)
+                goto err;
+
+        dev->_vblank_count = drm_alloc(sizeof(atomic_t) * num_crtcs,
+                                      DRM_MEM_DRIVER);
+        if (!dev->_vblank_count)
+                goto err;
+
+        dev->vblank_refcount = drm_alloc(sizeof(atomic_t) * num_crtcs,
+                                         DRM_MEM_DRIVER);
+        if (!dev->vblank_refcount)
+                goto err;
+
+        dev->vblank_enabled = drm_calloc(num_crtcs, sizeof(int),
+                                         DRM_MEM_DRIVER);
+        if (!dev->vblank_enabled)
+                goto err;
+
+        dev->last_vblank = drm_calloc(num_crtcs, sizeof(u32), DRM_MEM_DRIVER);
+        if (!dev->last_vblank)
+                goto err;
+
+        dev->vblank_premodeset = drm_calloc(num_crtcs, sizeof(u32),
+                                            DRM_MEM_DRIVER);
+        if (!dev->vblank_premodeset)
+                goto err;
+
+        dev->vblank_offset = drm_calloc(num_crtcs, sizeof(u32), DRM_MEM_DRIVER);
+        if (!dev->vblank_offset)
+                goto err;
+
+        /* Zero per-crtc vblank stuff */
+        for (i = 0; i < num_crtcs; i++) {
+                init_waitqueue_head(&dev->vbl_queue[i]);
+                INIT_LIST_HEAD(&dev->vbl_sigs[i]);
+                atomic_set(&dev->_vblank_count[i], 0);
+                atomic_set(&dev->vblank_refcount[i], 0);
+        }
+
+        return 0;
+
+err:
+        drm_vblank_cleanup(dev);
+        return ret;
+}
+EXPORT_SYMBOL(drm_vblank_init);
+
 /**
  * Install IRQ handler.
  *
@@ -109,17 +220,6 @@ static int drm_irq_install(struct drm_device * dev)
 
         DRM_DEBUG("irq=%d\n", dev->irq);
 
-        if (drm_core_check_feature(dev, DRIVER_IRQ_VBL)) {
-                init_waitqueue_head(&dev->vbl_queue);
-
-                spin_lock_init(&dev->vbl_lock);
-
-                INIT_LIST_HEAD(&dev->vbl_sigs);
-                INIT_LIST_HEAD(&dev->vbl_sigs2);
-
-                dev->vbl_pending = 0;
-        }
-
         /* Before installing handler */
         dev->driver->irq_preinstall(dev);
 
@@ -137,9 +237,14 @@ static int drm_irq_install(struct drm_device * dev)
         }
 
         /* After installing handler */
-        dev->driver->irq_postinstall(dev);
+        ret = dev->driver->irq_postinstall(dev);
+        if (ret < 0) {
+                mutex_lock(&dev->struct_mutex);
+                dev->irq_enabled = 0;
+                mutex_unlock(&dev->struct_mutex);
+        }
 
-        return 0;
+        return ret;
 }
 
 /**
@@ -170,6 +275,8 @@ int drm_irq_uninstall(struct drm_device * dev)
 
         free_irq(dev->irq, dev);
 
+        drm_vblank_cleanup(dev);
+
         dev->locked_tasklet_func = NULL;
 
         return 0;
@@ -214,6 +321,148 @@ int drm_control(struct drm_device *dev, void *data,
 }
 
 /**
+ * drm_vblank_count - retrieve "cooked" vblank counter value
+ * @dev: DRM device
+ * @crtc: which counter to retrieve
+ *
+ * Fetches the "cooked" vblank count value that represents the number of
+ * vblank events since the system was booted, including lost events due to
+ * modesetting activity.
+ */
+u32 drm_vblank_count(struct drm_device *dev, int crtc)
+{
+        return atomic_read(&dev->_vblank_count[crtc]) +
+                dev->vblank_offset[crtc];
+}
+EXPORT_SYMBOL(drm_vblank_count);
+
+/**
+ * drm_update_vblank_count - update the master vblank counter
+ * @dev: DRM device
+ * @crtc: counter to update
+ *
+ * Call back into the driver to update the appropriate vblank counter
+ * (specified by @crtc).  Deal with wraparound, if it occurred, and
+ * update the last read value so we can deal with wraparound on the next
+ * call if necessary.
+ */
+void drm_update_vblank_count(struct drm_device *dev, int crtc)
+{
+        unsigned long irqflags;
+        u32 cur_vblank, diff;
+
+        /*
+         * Interrupts were disabled prior to this call, so deal with counter
+         * wrap if needed.
+         * NOTE!  It's possible we lost a full dev->max_vblank_count events
+         * here if the register is small or we had vblank interrupts off for
+         * a long time.
+         */
+        cur_vblank = dev->driver->get_vblank_counter(dev, crtc);
+        spin_lock_irqsave(&dev->vbl_lock, irqflags);
+        if (cur_vblank < dev->last_vblank[crtc]) {
+                diff = dev->max_vblank_count -
+                        dev->last_vblank[crtc];
+                diff += cur_vblank;
+        } else {
+                diff = cur_vblank - dev->last_vblank[crtc];
+        }
+        dev->last_vblank[crtc] = cur_vblank;
+        spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
+
+        atomic_add(diff, &dev->_vblank_count[crtc]);
+}
+EXPORT_SYMBOL(drm_update_vblank_count);
+
+/**
+ * drm_vblank_get - get a reference count on vblank events
+ * @dev: DRM device
+ * @crtc: which CRTC to own
+ *
+ * Acquire a reference count on vblank events to avoid having them disabled
+ * while in use.  Note callers will probably want to update the master counter
+ * using drm_update_vblank_count() above before calling this routine so that
+ * wakeups occur on the right vblank event.
+ *
+ * RETURNS
+ * Zero on success, nonzero on failure.
+ */
+int drm_vblank_get(struct drm_device *dev, int crtc)
+{
+        unsigned long irqflags;
+        int ret = 0;
+
+        spin_lock_irqsave(&dev->vbl_lock, irqflags);
+        /* Going from 0->1 means we have to enable interrupts again */
+        if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1 &&
+            !dev->vblank_enabled[crtc]) {
+                ret = dev->driver->enable_vblank(dev, crtc);
+                if (ret)
+                        atomic_dec(&dev->vblank_refcount[crtc]);
+                else
+                        dev->vblank_enabled[crtc] = 1;
+        }
+        spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
+
+        return ret;
+}
+EXPORT_SYMBOL(drm_vblank_get);
+
+/**
+ * drm_vblank_put - give up ownership of vblank events
+ * @dev: DRM device
+ * @crtc: which counter to give up
+ *
+ * Release ownership of a given vblank counter, turning off interrupts
+ * if possible.
+ */
+void drm_vblank_put(struct drm_device *dev, int crtc)
+{
+        /* Last user schedules interrupt disable */
+        if (atomic_dec_and_test(&dev->vblank_refcount[crtc]))
+            mod_timer(&dev->vblank_disable_timer, jiffies + 5*DRM_HZ);
+}
+EXPORT_SYMBOL(drm_vblank_put);
+
+/**
+ * drm_modeset_ctl - handle vblank event counter changes across mode switch
+ * @DRM_IOCTL_ARGS: standard ioctl arguments
+ *
+ * Applications should call the %_DRM_PRE_MODESET and %_DRM_POST_MODESET
+ * ioctls around modesetting so that any lost vblank events are accounted for.
+ */
+int drm_modeset_ctl(struct drm_device *dev, void *data,
+                    struct drm_file *file_priv)
+{
+        struct drm_modeset_ctl *modeset = data;
+        int crtc, ret = 0;
+        u32 new;
+
+        crtc = modeset->arg;
+        if (crtc >= dev->num_crtcs) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        switch (modeset->cmd) {
+        case _DRM_PRE_MODESET:
+                dev->vblank_premodeset[crtc] =
+                        dev->driver->get_vblank_counter(dev, crtc);
+                break;
+        case _DRM_POST_MODESET:
+                new = dev->driver->get_vblank_counter(dev, crtc);
+                dev->vblank_offset[crtc] = dev->vblank_premodeset[crtc] - new;
+                break;
+        default:
+                ret = -EINVAL;
+                break;
+        }
+
+out:
+        return ret;
+}
+
+/**
  * Wait for VBLANK.
  *
  * \param inode device inode.
@@ -232,12 +481,13 @@ int drm_control(struct drm_device *dev, void *data,
  *
  * If a signal is not requested, then calls vblank_wait().
  */
-int drm_wait_vblank(struct drm_device *dev, void *data, struct drm_file *file_priv)
+int drm_wait_vblank(struct drm_device *dev, void *data,
+                    struct drm_file *file_priv)
 {
         union drm_wait_vblank *vblwait = data;
         struct timeval now;
         int ret = 0;
-        unsigned int flags, seq;
+        unsigned int flags, seq, crtc;
 
         if ((!dev->irq) || (!dev->irq_enabled))
                 return -EINVAL;
@@ -251,13 +501,13 @@ int drm_wait_vblank(struct drm_device *dev, void *data, struct drm_file *file_pr
         }
 
         flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;
+        crtc = flags & _DRM_VBLANK_SECONDARY ? 1 : 0;
 
-        if (!drm_core_check_feature(dev, (flags & _DRM_VBLANK_SECONDARY) ?
-                                    DRIVER_IRQ_VBL2 : DRIVER_IRQ_VBL))
+        if (crtc >= dev->num_crtcs)
                 return -EINVAL;
 
-        seq = atomic_read((flags & _DRM_VBLANK_SECONDARY) ? &dev->vbl_received2
-                          : &dev->vbl_received);
+        drm_update_vblank_count(dev, crtc);
+        seq = drm_vblank_count(dev, crtc);
 
         switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) {
         case _DRM_VBLANK_RELATIVE:
@@ -276,8 +526,7 @@ int drm_wait_vblank(struct drm_device *dev, void *data, struct drm_file *file_pr
 
         if (flags & _DRM_VBLANK_SIGNAL) {
                 unsigned long irqflags;
-                struct list_head *vbl_sigs = (flags & _DRM_VBLANK_SECONDARY)
-                                      ? &dev->vbl_sigs2 : &dev->vbl_sigs;
+                struct list_head *vbl_sigs = &dev->vbl_sigs[crtc];
                 struct drm_vbl_sig *vbl_sig;
 
                 spin_lock_irqsave(&dev->vbl_lock, irqflags);
@@ -298,22 +547,26 @@ int drm_wait_vblank(struct drm_device *dev, void *data, struct drm_file *file_pr
                         }
                 }
 
-                if (dev->vbl_pending >= 100) {
+                if (atomic_read(&dev->vbl_signal_pending) >= 100) {
                         spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
                         return -EBUSY;
                 }
 
-                dev->vbl_pending++;
-
                 spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 
-                if (!
-                    (vbl_sig =
-                     drm_alloc(sizeof(struct drm_vbl_sig), DRM_MEM_DRIVER))) {
+                vbl_sig = drm_calloc(1, sizeof(struct drm_vbl_sig),
+                                     DRM_MEM_DRIVER);
+                if (!vbl_sig)
                         return -ENOMEM;
+
+                ret = drm_vblank_get(dev, crtc);
+                if (ret) {
+                        drm_free(vbl_sig, sizeof(struct drm_vbl_sig),
+                                 DRM_MEM_DRIVER);
+                        return ret;
                 }
 
-                memset((void *)vbl_sig, 0, sizeof(*vbl_sig));
+                atomic_inc(&dev->vbl_signal_pending);
 
                 vbl_sig->sequence = vblwait->request.sequence;
                 vbl_sig->info.si_signo = vblwait->request.signal;
@@ -327,17 +580,20 @@ int drm_wait_vblank(struct drm_device *dev, void *data, struct drm_file *file_pr
 
                 vblwait->reply.sequence = seq;
         } else {
-                if (flags & _DRM_VBLANK_SECONDARY) {
-                        if (dev->driver->vblank_wait2)
-                                ret = dev->driver->vblank_wait2(dev, &vblwait->request.sequence);
-                } else if (dev->driver->vblank_wait)
-                        ret =
-                            dev->driver->vblank_wait(dev,
-                                                     &vblwait->request.sequence);
-
+                unsigned long cur_vblank;
+
+                ret = drm_vblank_get(dev, crtc);
+                if (ret)
+                        return ret;
+                DRM_WAIT_ON(ret, dev->vbl_queue[crtc], 3 * DRM_HZ,
+                            (((cur_vblank = drm_vblank_count(dev, crtc))
+                              - vblwait->request.sequence) <= (1 << 23)));
+                drm_vblank_put(dev, crtc);
                 do_gettimeofday(&now);
+
                 vblwait->reply.tval_sec = now.tv_sec;
                 vblwait->reply.tval_usec = now.tv_usec;
+                vblwait->reply.sequence = cur_vblank;
         }
 
       done:
@@ -348,44 +604,57 @@ int drm_wait_vblank(struct drm_device *dev, void *data, struct drm_file *file_pr
  * Send the VBLANK signals.
  *
  * \param dev DRM device.
+ * \param crtc CRTC where the vblank event occurred
  *
  * Sends a signal for each task in drm_device::vbl_sigs and empties the list.
  *
  * If a signal is not requested, then calls vblank_wait().
  */
-void drm_vbl_send_signals(struct drm_device * dev)
+static void drm_vbl_send_signals(struct drm_device * dev, int crtc)
 {
+        struct drm_vbl_sig *vbl_sig, *tmp;
+        struct list_head *vbl_sigs;
+        unsigned int vbl_seq;
         unsigned long flags;
-        int i;
 
         spin_lock_irqsave(&dev->vbl_lock, flags);
 
-        for (i = 0; i < 2; i++) {
-                struct drm_vbl_sig *vbl_sig, *tmp;
-                struct list_head *vbl_sigs = i ? &dev->vbl_sigs2 : &dev->vbl_sigs;
-                unsigned int vbl_seq = atomic_read(i ? &dev->vbl_received2 :
-                                                   &dev->vbl_received);
+        vbl_sigs = &dev->vbl_sigs[crtc];
+        vbl_seq = drm_vblank_count(dev, crtc);
 
-                list_for_each_entry_safe(vbl_sig, tmp, vbl_sigs, head) {
-                        if ((vbl_seq - vbl_sig->sequence) <= (1 << 23)) {
-                                vbl_sig->info.si_code = vbl_seq;
-                                send_sig_info(vbl_sig->info.si_signo,
-                                              &vbl_sig->info, vbl_sig->task);
+        list_for_each_entry_safe(vbl_sig, tmp, vbl_sigs, head) {
+            if ((vbl_seq - vbl_sig->sequence) <= (1 << 23)) {
+                vbl_sig->info.si_code = vbl_seq;
+                send_sig_info(vbl_sig->info.si_signo,
+                              &vbl_sig->info, vbl_sig->task);
 
-                                list_del(&vbl_sig->head);
+                list_del(&vbl_sig->head);
 
-                                drm_free(vbl_sig, sizeof(*vbl_sig),
-                                         DRM_MEM_DRIVER);
-
-                                dev->vbl_pending--;
-                        }
-                }
+                drm_free(vbl_sig, sizeof(*vbl_sig),
+                         DRM_MEM_DRIVER);
+                atomic_dec(&dev->vbl_signal_pending);
+                drm_vblank_put(dev, crtc);
+            }
         }
 
         spin_unlock_irqrestore(&dev->vbl_lock, flags);
 }
 
-EXPORT_SYMBOL(drm_vbl_send_signals);
+/**
+ * drm_handle_vblank - handle a vblank event
+ * @dev: DRM device
+ * @crtc: where this event occurred
+ *
+ * Drivers should call this routine in their vblank interrupt handlers to
+ * update the vblank counter and send any signals that may be pending.
+ */
+void drm_handle_vblank(struct drm_device *dev, int crtc)
+{
+        drm_update_vblank_count(dev, crtc);
+        DRM_WAKEUP(&dev->vbl_queue[crtc]);
+        drm_vbl_send_signals(dev, crtc);
+}
+EXPORT_SYMBOL(drm_handle_vblank);
 
 /**
  * Tasklet wrapper function.