1 files changed, 623 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
new file mode 100644
index 000000000000..df036118b8b1
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -0,0 +1,623 @@
+/* i915_irq.c -- IRQ support for the I915 -*- linux-c -*-
+ */
+/*
+ * Copyright 2003 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#include "drmP.h"
+#include "drm.h"
+#include "i915_drm.h"
+#include "i915_drv.h"
+
+#define USER_INT_FLAG (1<<1)
+#define VSYNC_PIPEB_FLAG (1<<5)
+#define VSYNC_PIPEA_FLAG (1<<7)
+
+#define MAX_NOPID ((u32)~0)
+
+/**
+ * Emit blits for scheduled buffer swaps.
+ *
+ * This function will be called with the HW lock held.
+ */
+static void i915_vblank_tasklet(struct drm_device *dev)
+{
+        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+        unsigned long irqflags;
+        struct list_head *list, *tmp, hits, *hit;
+        int nhits, nrects, slice[2], upper[2], lower[2], i;
+        unsigned counter[2] = { atomic_read(&dev->vbl_received),
+                                atomic_read(&dev->vbl_received2) };
+        struct drm_drawable_info *drw;
+        drm_i915_sarea_t *sarea_priv = dev_priv->sarea_priv;
+        u32 cpp = dev_priv->cpp;
+        u32 cmd = (cpp == 4) ? (XY_SRC_COPY_BLT_CMD |
+                                XY_SRC_COPY_BLT_WRITE_ALPHA |
+                                XY_SRC_COPY_BLT_WRITE_RGB)
+                             : XY_SRC_COPY_BLT_CMD;
+        u32 src_pitch = sarea_priv->pitch * cpp;
+        u32 dst_pitch = sarea_priv->pitch * cpp;
+        u32 ropcpp = (0xcc << 16) | ((cpp - 1) << 24);
+        RING_LOCALS;
+
+        if (IS_I965G(dev) && sarea_priv->front_tiled) {
+                cmd |= XY_SRC_COPY_BLT_DST_TILED;
+                dst_pitch >>= 2;
+        }
+        if (IS_I965G(dev) && sarea_priv->back_tiled) {
+                cmd |= XY_SRC_COPY_BLT_SRC_TILED;
+                src_pitch >>= 2;
+        }
+
+        DRM_DEBUG("\n");
+
+        INIT_LIST_HEAD(&hits);
+
+        nhits = nrects = 0;
+
+        spin_lock_irqsave(&dev_priv->swaps_lock, irqflags);
+
+        /* Find buffer swaps scheduled for this vertical blank */
+        list_for_each_safe(list, tmp, &dev_priv->vbl_swaps.head) {
+                drm_i915_vbl_swap_t *vbl_swap =
+                        list_entry(list, drm_i915_vbl_swap_t, head);
+
+                if ((counter[vbl_swap->pipe] - vbl_swap->sequence) > (1<<23))
+                        continue;
+
+                list_del(list);
+                dev_priv->swaps_pending--;
+
+                spin_unlock(&dev_priv->swaps_lock);
+                spin_lock(&dev->drw_lock);
+
+                drw = drm_get_drawable_info(dev, vbl_swap->drw_id);
+
+                if (!drw) {
+                        spin_unlock(&dev->drw_lock);
+                        drm_free(vbl_swap, sizeof(*vbl_swap), DRM_MEM_DRIVER);
+                        spin_lock(&dev_priv->swaps_lock);
+                        continue;
+                }
+
+                list_for_each(hit, &hits) {
+                        drm_i915_vbl_swap_t *swap_cmp =
+                                list_entry(hit, drm_i915_vbl_swap_t, head);
+                        struct drm_drawable_info *drw_cmp =
+                                drm_get_drawable_info(dev, swap_cmp->drw_id);
+
+                        if (drw_cmp &&
+                            drw_cmp->rects[0].y1 > drw->rects[0].y1) {
+                                list_add_tail(list, hit);
+                                break;
+                        }
+                }
+
+                spin_unlock(&dev->drw_lock);
+
+                /* List of hits was empty, or we reached the end of it */
+                if (hit == &hits)
+                        list_add_tail(list, hits.prev);
+
+                nhits++;
+
+                spin_lock(&dev_priv->swaps_lock);
+        }
+
+        if (nhits == 0) {
+                spin_unlock_irqrestore(&dev_priv->swaps_lock, irqflags);
+                return;
+        }
+
+        spin_unlock(&dev_priv->swaps_lock);
+
+        i915_kernel_lost_context(dev);
+
+        if (IS_I965G(dev)) {
+                BEGIN_LP_RING(4);
+
+                OUT_RING(GFX_OP_DRAWRECT_INFO_I965);
+                OUT_RING(0);
+                OUT_RING(((sarea_priv->width - 1) & 0xffff) | ((sarea_priv->height - 1) << 16));
+                OUT_RING(0);
+                ADVANCE_LP_RING();
+        } else {
+                BEGIN_LP_RING(6);
+
+                OUT_RING(GFX_OP_DRAWRECT_INFO);
+                OUT_RING(0);
+                OUT_RING(0);
+                OUT_RING(sarea_priv->width | sarea_priv->height << 16);
+                OUT_RING(sarea_priv->width | sarea_priv->height << 16);
+                OUT_RING(0);
+
+                ADVANCE_LP_RING();
+        }
+
+        sarea_priv->ctxOwner = DRM_KERNEL_CONTEXT;
+
+        upper[0] = upper[1] = 0;
+        slice[0] = max(sarea_priv->pipeA_h / nhits, 1);
+        slice[1] = max(sarea_priv->pipeB_h / nhits, 1);
+        lower[0] = sarea_priv->pipeA_y + slice[0];
+        lower[1] = sarea_priv->pipeB_y + slice[0];
+
+        spin_lock(&dev->drw_lock);
+
+        /* Emit blits for buffer swaps, partitioning both outputs into as many
+         * slices as there are buffer swaps scheduled in order to avoid tearing
+         * (based on the assumption that a single buffer swap would always
+         * complete before scanout starts).
+         */
+        for (i = 0; i++ < nhits;
+             upper[0] = lower[0], lower[0] += slice[0],
+             upper[1] = lower[1], lower[1] += slice[1]) {
+                if (i == nhits)
+                        lower[0] = lower[1] = sarea_priv->height;
+
+                list_for_each(hit, &hits) {
+                        drm_i915_vbl_swap_t *swap_hit =
+                                list_entry(hit, drm_i915_vbl_swap_t, head);
+                        struct drm_clip_rect *rect;
+                        int num_rects, pipe;
+                        unsigned short top, bottom;
+
+                        drw = drm_get_drawable_info(dev, swap_hit->drw_id);
+
+                        if (!drw)
+                                continue;
+
+                        rect = drw->rects;
+                        pipe = swap_hit->pipe;
+                        top = upper[pipe];
+                        bottom = lower[pipe];
+
+                        for (num_rects = drw->num_rects; num_rects--; rect++) {
+                                int y1 = max(rect->y1, top);
+                                int y2 = min(rect->y2, bottom);
+
+                                if (y1 >= y2)
+                                        continue;
+
+                                BEGIN_LP_RING(8);
+
+                                OUT_RING(cmd);
+                                OUT_RING(ropcpp | dst_pitch);
+                                OUT_RING((y1 << 16) | rect->x1);
+                                OUT_RING((y2 << 16) | rect->x2);
+                                OUT_RING(sarea_priv->front_offset);
+                                OUT_RING((y1 << 16) | rect->x1);
+                                OUT_RING(src_pitch);
+                                OUT_RING(sarea_priv->back_offset);
+
+                                ADVANCE_LP_RING();
+                        }
+                }
+        }
+
+        spin_unlock_irqrestore(&dev->drw_lock, irqflags);
+
+        list_for_each_safe(hit, tmp, &hits) {
+                drm_i915_vbl_swap_t *swap_hit =
+                        list_entry(hit, drm_i915_vbl_swap_t, head);
+
+                list_del(hit);
+
+                drm_free(swap_hit, sizeof(*swap_hit), DRM_MEM_DRIVER);
+        }
+}
+
+irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
+{
+        struct drm_device *dev = (struct drm_device *) arg;
+        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+        u16 temp;
+        u32 pipea_stats, pipeb_stats;
+
+        pipea_stats = I915_READ(I915REG_PIPEASTAT);
+        pipeb_stats = I915_READ(I915REG_PIPEBSTAT);
+
+        temp = I915_READ16(I915REG_INT_IDENTITY_R);
+
+        temp &= (USER_INT_FLAG | VSYNC_PIPEA_FLAG | VSYNC_PIPEB_FLAG);
+
+        DRM_DEBUG("%s flag=%08x\n", __FUNCTION__, temp);
+
+        if (temp == 0)
+                return IRQ_NONE;
+
+        I915_WRITE16(I915REG_INT_IDENTITY_R, temp);
+        (void) I915_READ16(I915REG_INT_IDENTITY_R);
+        DRM_READMEMORYBARRIER();
+
+        dev_priv->sarea_priv->last_dispatch = READ_BREADCRUMB(dev_priv);
+
+        if (temp & USER_INT_FLAG)
+                DRM_WAKEUP(&dev_priv->irq_queue);
+
+        if (temp & (VSYNC_PIPEA_FLAG | VSYNC_PIPEB_FLAG)) {
+                int vblank_pipe = dev_priv->vblank_pipe;
+
+                if ((vblank_pipe &
+                     (DRM_I915_VBLANK_PIPE_A | DRM_I915_VBLANK_PIPE_B))
+                    == (DRM_I915_VBLANK_PIPE_A | DRM_I915_VBLANK_PIPE_B)) {
+                        if (temp & VSYNC_PIPEA_FLAG)
+                                atomic_inc(&dev->vbl_received);
+                        if (temp & VSYNC_PIPEB_FLAG)
+                                atomic_inc(&dev->vbl_received2);
+                } else if (((temp & VSYNC_PIPEA_FLAG) &&
+                            (vblank_pipe & DRM_I915_VBLANK_PIPE_A)) ||
+                           ((temp & VSYNC_PIPEB_FLAG) &&
+                            (vblank_pipe & DRM_I915_VBLANK_PIPE_B)))
+                        atomic_inc(&dev->vbl_received);
+
+                DRM_WAKEUP(&dev->vbl_queue);
+                drm_vbl_send_signals(dev);
+
+                if (dev_priv->swaps_pending > 0)
+                        drm_locked_tasklet(dev, i915_vblank_tasklet);
+                I915_WRITE(I915REG_PIPEASTAT,
+                        pipea_stats|I915_VBLANK_INTERRUPT_ENABLE|
+                        I915_VBLANK_CLEAR);
+                I915_WRITE(I915REG_PIPEBSTAT,
+                        pipeb_stats|I915_VBLANK_INTERRUPT_ENABLE|
+                        I915_VBLANK_CLEAR);
+        }
+
+        return IRQ_HANDLED;
+}
+
+static int i915_emit_irq(struct drm_device * dev)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        RING_LOCALS;
+
+        i915_kernel_lost_context(dev);
+
+        DRM_DEBUG("\n");
+
+        dev_priv->sarea_priv->last_enqueue = ++dev_priv->counter;
+
+        if (dev_priv->counter > 0x7FFFFFFFUL)
+                dev_priv->sarea_priv->last_enqueue = dev_priv->counter = 1;
+
+        BEGIN_LP_RING(6);
+        OUT_RING(CMD_STORE_DWORD_IDX);
+        OUT_RING(20);
+        OUT_RING(dev_priv->counter);
+        OUT_RING(0);
+        OUT_RING(0);
+        OUT_RING(GFX_OP_USER_INTERRUPT);
+        ADVANCE_LP_RING();
+
+        return dev_priv->counter;
+}
+
+static int i915_wait_irq(struct drm_device * dev, int irq_nr)
+{
+        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+        int ret = 0;
+
+        DRM_DEBUG("irq_nr=%d breadcrumb=%d\n", irq_nr,
+                  READ_BREADCRUMB(dev_priv));
+
+        if (READ_BREADCRUMB(dev_priv) >= irq_nr)
+                return 0;
+
+        dev_priv->sarea_priv->perf_boxes |= I915_BOX_WAIT;
+
+        DRM_WAIT_ON(ret, dev_priv->irq_queue, 3 * DRM_HZ,
+                    READ_BREADCRUMB(dev_priv) >= irq_nr);
+
+        if (ret == -EBUSY) {
+                DRM_ERROR("EBUSY -- rec: %d emitted: %d\n",
+                          READ_BREADCRUMB(dev_priv), (int)dev_priv->counter);
+        }
+
+        dev_priv->sarea_priv->last_dispatch = READ_BREADCRUMB(dev_priv);
+        return ret;
+}
+
+static int i915_driver_vblank_do_wait(struct drm_device *dev, unsigned int *sequence,
+                                      atomic_t *counter)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        unsigned int cur_vblank;
+        int ret = 0;
+
+        if (!dev_priv) {
+                DRM_ERROR("called with no initialization\n");
+                return -EINVAL;
+        }
+
+        DRM_WAIT_ON(ret, dev->vbl_queue, 3 * DRM_HZ,
+                    (((cur_vblank = atomic_read(counter))
+                        - *sequence) <= (1<<23)));
+
+        *sequence = cur_vblank;
+
+        return ret;
+}
+
+
+int i915_driver_vblank_wait(struct drm_device *dev, unsigned int *sequence)
+{
+        return i915_driver_vblank_do_wait(dev, sequence, &dev->vbl_received);
+}
+
+int i915_driver_vblank_wait2(struct drm_device *dev, unsigned int *sequence)
+{
+        return i915_driver_vblank_do_wait(dev, sequence, &dev->vbl_received2);
+}
+
+/* Needs the lock as it touches the ring.
+ */
+int i915_irq_emit(struct drm_device *dev, void *data,
+                         struct drm_file *file_priv)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        drm_i915_irq_emit_t *emit = data;
+        int result;
+
+        LOCK_TEST_WITH_RETURN(dev, file_priv);
+
+        if (!dev_priv) {
+                DRM_ERROR("called with no initialization\n");
+                return -EINVAL;
+        }
+
+        result = i915_emit_irq(dev);
+
+        if (DRM_COPY_TO_USER(emit->irq_seq, &result, sizeof(int))) {
+                DRM_ERROR("copy_to_user\n");
+                return -EFAULT;
+        }
+
+        return 0;
+}
+
+/* Doesn't need the hardware lock.
+ */
+int i915_irq_wait(struct drm_device *dev, void *data,
+                         struct drm_file *file_priv)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        drm_i915_irq_wait_t *irqwait = data;
+
+        if (!dev_priv) {
+                DRM_ERROR("called with no initialization\n");
+                return -EINVAL;
+        }
+
+        return i915_wait_irq(dev, irqwait->irq_seq);
+}
+
+static void i915_enable_interrupt (struct drm_device *dev)
+{
+        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+        u16 flag;
+
+        flag = 0;
+        if (dev_priv->vblank_pipe & DRM_I915_VBLANK_PIPE_A)
+                flag |= VSYNC_PIPEA_FLAG;
+        if (dev_priv->vblank_pipe & DRM_I915_VBLANK_PIPE_B)
+                flag |= VSYNC_PIPEB_FLAG;
+
+        I915_WRITE16(I915REG_INT_ENABLE_R, USER_INT_FLAG | flag);
+}
+
+/* Set the vblank monitor pipe
+ */
+int i915_vblank_pipe_set(struct drm_device *dev, void *data,
+                         struct drm_file *file_priv)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        drm_i915_vblank_pipe_t *pipe = data;
+
+        if (!dev_priv) {
+                DRM_ERROR("called with no initialization\n");
+                return -EINVAL;
+        }
+
+        if (pipe->pipe & ~(DRM_I915_VBLANK_PIPE_A|DRM_I915_VBLANK_PIPE_B)) {
+                DRM_ERROR("called with invalid pipe 0x%x\n", pipe->pipe);
+                return -EINVAL;
+        }
+
+        dev_priv->vblank_pipe = pipe->pipe;
+
+        i915_enable_interrupt (dev);
+
+        return 0;
+}
+
+int i915_vblank_pipe_get(struct drm_device *dev, void *data,
+                         struct drm_file *file_priv)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        drm_i915_vblank_pipe_t *pipe = data;
+        u16 flag;
+
+        if (!dev_priv) {
+                DRM_ERROR("called with no initialization\n");
+                return -EINVAL;
+        }
+
+        flag = I915_READ(I915REG_INT_ENABLE_R);
+        pipe->pipe = 0;
+        if (flag & VSYNC_PIPEA_FLAG)
+                pipe->pipe |= DRM_I915_VBLANK_PIPE_A;
+        if (flag & VSYNC_PIPEB_FLAG)
+                pipe->pipe |= DRM_I915_VBLANK_PIPE_B;
+
+        return 0;
+}
+
+/**
+ * Schedule buffer swap at given vertical blank.
+ */
+int i915_vblank_swap(struct drm_device *dev, void *data,
+                     struct drm_file *file_priv)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        drm_i915_vblank_swap_t *swap = data;
+        drm_i915_vbl_swap_t *vbl_swap;
+        unsigned int pipe, seqtype, curseq;
+        unsigned long irqflags;
+        struct list_head *list;
+
+        if (!dev_priv) {
+                DRM_ERROR("%s called with no initialization\n", __func__);
+                return -EINVAL;
+        }
+
+        if (dev_priv->sarea_priv->rotation) {
+                DRM_DEBUG("Rotation not supported\n");
+                return -EINVAL;
+        }
+
+        if (swap->seqtype & ~(_DRM_VBLANK_RELATIVE | _DRM_VBLANK_ABSOLUTE |
+                             _DRM_VBLANK_SECONDARY | _DRM_VBLANK_NEXTONMISS)) {
+                DRM_ERROR("Invalid sequence type 0x%x\n", swap->seqtype);
+                return -EINVAL;
+        }
+
+        pipe = (swap->seqtype & _DRM_VBLANK_SECONDARY) ? 1 : 0;
+
+        seqtype = swap->seqtype & (_DRM_VBLANK_RELATIVE | _DRM_VBLANK_ABSOLUTE);
+
+        if (!(dev_priv->vblank_pipe & (1 << pipe))) {
+                DRM_ERROR("Invalid pipe %d\n", pipe);
+                return -EINVAL;
+        }
+
+        spin_lock_irqsave(&dev->drw_lock, irqflags);
+
+        if (!drm_get_drawable_info(dev, swap->drawable)) {
+                spin_unlock_irqrestore(&dev->drw_lock, irqflags);
+                DRM_DEBUG("Invalid drawable ID %d\n", swap->drawable);
+                return -EINVAL;
+        }
+
+        spin_unlock_irqrestore(&dev->drw_lock, irqflags);
+
+        curseq = atomic_read(pipe ? &dev->vbl_received2 : &dev->vbl_received);
+
+        if (seqtype == _DRM_VBLANK_RELATIVE)
+                swap->sequence += curseq;
+
+        if ((curseq - swap->sequence) <= (1<<23)) {
+                if (swap->seqtype & _DRM_VBLANK_NEXTONMISS) {
+                        swap->sequence = curseq + 1;
+                } else {
+                        DRM_DEBUG("Missed target sequence\n");
+                        return -EINVAL;
+                }
+        }
+
+        spin_lock_irqsave(&dev_priv->swaps_lock, irqflags);
+
+        list_for_each(list, &dev_priv->vbl_swaps.head) {
+                vbl_swap = list_entry(list, drm_i915_vbl_swap_t, head);
+
+                if (vbl_swap->drw_id == swap->drawable &&
+                    vbl_swap->pipe == pipe &&
+                    vbl_swap->sequence == swap->sequence) {
+                        spin_unlock_irqrestore(&dev_priv->swaps_lock, irqflags);
+                        DRM_DEBUG("Already scheduled\n");
+                        return 0;
+                }
+        }
+
+        spin_unlock_irqrestore(&dev_priv->swaps_lock, irqflags);
+
+        if (dev_priv->swaps_pending >= 100) {
+                DRM_DEBUG("Too many swaps queued\n");
+                return -EBUSY;
+        }
+
+        vbl_swap = drm_calloc(1, sizeof(*vbl_swap), DRM_MEM_DRIVER);
+
+        if (!vbl_swap) {
+                DRM_ERROR("Failed to allocate memory to queue swap\n");
+                return -ENOMEM;
+        }
+
+        DRM_DEBUG("\n");
+
+        vbl_swap->drw_id = swap->drawable;
+        vbl_swap->pipe = pipe;
+        vbl_swap->sequence = swap->sequence;
+
+        spin_lock_irqsave(&dev_priv->swaps_lock, irqflags);
+
+        list_add_tail(&vbl_swap->head, &dev_priv->vbl_swaps.head);
+        dev_priv->swaps_pending++;
+
+        spin_unlock_irqrestore(&dev_priv->swaps_lock, irqflags);
+
+        return 0;
+}
+
+/* drm_dma.h hooks
+*/
+void i915_driver_irq_preinstall(struct drm_device * dev)
+{
+        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+
+        I915_WRITE16(I915REG_HWSTAM, 0xfffe);
+        I915_WRITE16(I915REG_INT_MASK_R, 0x0);
+        I915_WRITE16(I915REG_INT_ENABLE_R, 0x0);
+}
+
+void i915_driver_irq_postinstall(struct drm_device * dev)
+{
+        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+
+        spin_lock_init(&dev_priv->swaps_lock);
+        INIT_LIST_HEAD(&dev_priv->vbl_swaps.head);
+        dev_priv->swaps_pending = 0;
+
+        if (!dev_priv->vblank_pipe)
+                dev_priv->vblank_pipe = DRM_I915_VBLANK_PIPE_A;
+        i915_enable_interrupt(dev);
+        DRM_INIT_WAITQUEUE(&dev_priv->irq_queue);
+}
+
+void i915_driver_irq_uninstall(struct drm_device * dev)
+{
+        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+        u16 temp;
+
+        if (!dev_priv)
+                return;
+
+        I915_WRITE16(I915REG_HWSTAM, 0xffff);
+        I915_WRITE16(I915REG_INT_MASK_R, 0xffff);
+        I915_WRITE16(I915REG_INT_ENABLE_R, 0x0);
+
+        temp = I915_READ16(I915REG_INT_IDENTITY_R);
+        I915_WRITE16(I915REG_INT_IDENTITY_R, temp);
+}