drm: Rework vblank-wait handling to allow interrupt reduction.

Previously, drivers supporting vblank interrupt waits would run the interrupt
all the time, or all the time that any 3d client was running, preventing the
CPU from sleeping for long when the system was otherwise idle.  Now, interrupts
are disabled any time that no client is waiting on a vblank event. The new
method uses vblank counters on the chipsets when the interrupts are turned
off, rather than counting interrupts, so that we can continue to present
accurate vblank numbers.

Co-author: Michel Dänzer <michel@tungstengraphics.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 35 insertions, 20 deletions

diff --git a/drivers/gpu/drm/r128/r128_irq.c b/drivers/gpu/drm/r128/r128_irq.c
index c76fdca7662d..d7349012a680 100644
--- a/drivers/gpu/drm/r128/r128_irq.c
+++ b/drivers/gpu/drm/r128/r128_irq.c
@@ -35,6 +35,16 @@
 #include "r128_drm.h"
 #include "r128_drv.h"
 
+u32 r128_get_vblank_counter(struct drm_device *dev, int crtc)
+{
+        const drm_r128_private_t *dev_priv = dev->dev_private;
+
+        if (crtc != 0)
+                return 0;
+
+        return atomic_read(&dev_priv->vbl_received);
+}
+
 irqreturn_t r128_driver_irq_handler(DRM_IRQ_ARGS)
 {
         struct drm_device *dev = (struct drm_device *) arg;
@@ -46,30 +56,38 @@ irqreturn_t r128_driver_irq_handler(DRM_IRQ_ARGS)
         /* VBLANK interrupt */
         if (status & R128_CRTC_VBLANK_INT) {
                 R128_WRITE(R128_GEN_INT_STATUS, R128_CRTC_VBLANK_INT_AK);
-                atomic_inc(&dev->vbl_received);
-                DRM_WAKEUP(&dev->vbl_queue);
-                drm_vbl_send_signals(dev);
+                atomic_inc(&dev_priv->vbl_received);
+                drm_handle_vblank(dev, 0);
                 return IRQ_HANDLED;
         }
         return IRQ_NONE;
 }
 
-int r128_driver_vblank_wait(struct drm_device * dev, unsigned int *sequence)
+int r128_enable_vblank(struct drm_device *dev, int crtc)
 {
-        unsigned int cur_vblank;
-        int ret = 0;
+        drm_r128_private_t *dev_priv = dev->dev_private;
 
-        /* Assume that the user has missed the current sequence number
-         * by about a day rather than she wants to wait for years
-         * using vertical blanks...
-         */
-        DRM_WAIT_ON(ret, dev->vbl_queue, 3 * DRM_HZ,
-                    (((cur_vblank = atomic_read(&dev->vbl_received))
-                      - *sequence) <= (1 << 23)));
+        if (crtc != 0) {
+                DRM_ERROR("%s:  bad crtc %d\n", __func__, crtc);
+                return -EINVAL;
+        }
 
-        *sequence = cur_vblank;
+        R128_WRITE(R128_GEN_INT_CNTL, R128_CRTC_VBLANK_INT_EN);
+        return 0;
+}
+
+void r128_disable_vblank(struct drm_device *dev, int crtc)
+{
+        if (crtc != 0)
+                DRM_ERROR("%s:  bad crtc %d\n", __func__, crtc);
 
-        return ret;
+        /*
+         * FIXME: implement proper interrupt disable by using the vblank
+         * counter register (if available)
+         *
+         * R128_WRITE(R128_GEN_INT_CNTL,
+         *            R128_READ(R128_GEN_INT_CNTL) & ~R128_CRTC_VBLANK_INT_EN);
+         */
 }
 
 void r128_driver_irq_preinstall(struct drm_device * dev)
@@ -82,12 +100,9 @@ void r128_driver_irq_preinstall(struct drm_device * dev)
         R128_WRITE(R128_GEN_INT_STATUS, R128_CRTC_VBLANK_INT_AK);
 }
 
-void r128_driver_irq_postinstall(struct drm_device * dev)
+int r128_driver_irq_postinstall(struct drm_device *dev)
 {
-        drm_r128_private_t *dev_priv = (drm_r128_private_t *) dev->dev_private;
-
-        /* Turn on VBL interrupt */
-        R128_WRITE(R128_GEN_INT_CNTL, R128_CRTC_VBLANK_INT_EN);
+        return drm_vblank_init(dev, 1);
 }
 
 void r128_driver_irq_uninstall(struct drm_device * dev)