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drm/i915/ringbuffer: Make IRQ refcnting atomic
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In order to enforce the correct memory barriers for irq get/put, we need
to perform the actual counting using atomic operations.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
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Chris Wilson committed Dec 14, 2010
1 parent 8d5203c commit b13c2b9
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Showing 4 changed files with 56 additions and 46 deletions.
37 changes: 20 additions & 17 deletions drivers/gpu/drm/i915/i915_gem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2000,17 +2000,19 @@ i915_do_wait_request(struct drm_device *dev, uint32_t seqno,
trace_i915_gem_request_wait_begin(dev, seqno);

ring->waiting_seqno = seqno;
ring->irq_get(ring);
if (interruptible)
ret = wait_event_interruptible(ring->irq_queue,
i915_seqno_passed(ring->get_seqno(ring), seqno)
|| atomic_read(&dev_priv->mm.wedged));
else
wait_event(ring->irq_queue,
i915_seqno_passed(ring->get_seqno(ring), seqno)
|| atomic_read(&dev_priv->mm.wedged));
ret = -ENODEV;
if (ring->irq_get(ring)) {
if (interruptible)
ret = wait_event_interruptible(ring->irq_queue,
i915_seqno_passed(ring->get_seqno(ring), seqno)
|| atomic_read(&dev_priv->mm.wedged));
else
wait_event(ring->irq_queue,
i915_seqno_passed(ring->get_seqno(ring), seqno)
|| atomic_read(&dev_priv->mm.wedged));

ring->irq_put(ring);
ring->irq_put(ring);
}
ring->waiting_seqno = 0;

trace_i915_gem_request_wait_end(dev, seqno);
Expand Down Expand Up @@ -3157,14 +3159,15 @@ i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
* generation is designed to be run atomically and so is
* lockless.
*/
ring->irq_get(ring);
ret = wait_event_interruptible(ring->irq_queue,
i915_seqno_passed(ring->get_seqno(ring), seqno)
|| atomic_read(&dev_priv->mm.wedged));
ring->irq_put(ring);
if (ring->irq_get(ring)) {
ret = wait_event_interruptible(ring->irq_queue,
i915_seqno_passed(ring->get_seqno(ring), seqno)
|| atomic_read(&dev_priv->mm.wedged));
ring->irq_put(ring);

if (ret == 0 && atomic_read(&dev_priv->mm.wedged))
ret = -EIO;
if (ret == 0 && atomic_read(&dev_priv->mm.wedged))
ret = -EIO;
}
}

if (ret == 0)
Expand Down
17 changes: 9 additions & 8 deletions drivers/gpu/drm/i915/i915_irq.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1186,10 +1186,9 @@ void i915_trace_irq_get(struct drm_device *dev, u32 seqno)
drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
struct intel_ring_buffer *ring = LP_RING(dev_priv);

if (dev_priv->trace_irq_seqno == 0)
ring->irq_get(ring);

dev_priv->trace_irq_seqno = seqno;
if (dev_priv->trace_irq_seqno == 0 &&
ring->irq_get(ring))
dev_priv->trace_irq_seqno = seqno;
}

static int i915_wait_irq(struct drm_device * dev, int irq_nr)
Expand All @@ -1211,10 +1210,12 @@ static int i915_wait_irq(struct drm_device * dev, int irq_nr)
if (master_priv->sarea_priv)
master_priv->sarea_priv->perf_boxes |= I915_BOX_WAIT;

ring->irq_get(ring);
DRM_WAIT_ON(ret, ring->irq_queue, 3 * DRM_HZ,
READ_BREADCRUMB(dev_priv) >= irq_nr);
ring->irq_put(ring);
ret = -ENODEV;
if (ring->irq_get(ring)) {
DRM_WAIT_ON(ret, ring->irq_queue, 3 * DRM_HZ,
READ_BREADCRUMB(dev_priv) >= irq_nr);
ring->irq_put(ring);
}

if (ret == -EBUSY) {
DRM_ERROR("EBUSY -- rec: %d emitted: %d\n",
Expand Down
44 changes: 25 additions & 19 deletions drivers/gpu/drm/i915/intel_ringbuffer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -327,34 +327,36 @@ ring_get_seqno(struct intel_ring_buffer *ring)
return intel_read_status_page(ring, I915_GEM_HWS_INDEX);
}

static void
static bool
render_ring_get_irq(struct intel_ring_buffer *ring)
{
struct drm_device *dev = ring->dev;

if (dev->irq_enabled && ++ring->irq_refcount == 1) {
if (!dev->irq_enabled)
return false;

if (atomic_inc_return(&ring->irq_refcount) == 1) {
drm_i915_private_t *dev_priv = dev->dev_private;
unsigned long irqflags;

spin_lock_irqsave(&dev_priv->irq_lock, irqflags);

if (HAS_PCH_SPLIT(dev))
ironlake_enable_graphics_irq(dev_priv,
GT_USER_INTERRUPT);
else
i915_enable_irq(dev_priv, I915_USER_INTERRUPT);

spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
}

return true;
}

static void
render_ring_put_irq(struct intel_ring_buffer *ring)
{
struct drm_device *dev = ring->dev;

BUG_ON(dev->irq_enabled && ring->irq_refcount == 0);
if (dev->irq_enabled && --ring->irq_refcount == 0) {
if (atomic_dec_and_test(&ring->irq_refcount)) {
drm_i915_private_t *dev_priv = dev->dev_private;
unsigned long irqflags;

Expand Down Expand Up @@ -417,27 +419,32 @@ ring_add_request(struct intel_ring_buffer *ring,
return 0;
}

static void
static bool
ring_get_irq(struct intel_ring_buffer *ring, u32 flag)
{
struct drm_device *dev = ring->dev;

if (dev->irq_enabled && ++ring->irq_refcount == 1) {
if (!dev->irq_enabled)
return false;

if (atomic_inc_return(&ring->irq_refcount) == 1) {
drm_i915_private_t *dev_priv = dev->dev_private;
unsigned long irqflags;

spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
ironlake_enable_graphics_irq(dev_priv, flag);
spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
}

return true;
}

static void
ring_put_irq(struct intel_ring_buffer *ring, u32 flag)
{
struct drm_device *dev = ring->dev;

if (dev->irq_enabled && --ring->irq_refcount == 0) {
if (atomic_dec_and_test(&ring->irq_refcount)) {
drm_i915_private_t *dev_priv = dev->dev_private;
unsigned long irqflags;

Expand All @@ -447,16 +454,15 @@ ring_put_irq(struct intel_ring_buffer *ring, u32 flag)
}
}


static void
static bool
bsd_ring_get_irq(struct intel_ring_buffer *ring)
{
ring_get_irq(ring, GT_BSD_USER_INTERRUPT);
return ring_get_irq(ring, GT_BSD_USER_INTERRUPT);
}
static void
bsd_ring_put_irq(struct intel_ring_buffer *ring)
{
ring_put_irq(ring, GT_BSD_USER_INTERRUPT);
ring_put_irq(ring, GT_BSD_USER_INTERRUPT);
}

static int
Expand Down Expand Up @@ -846,16 +852,16 @@ gen6_ring_dispatch_execbuffer(struct intel_ring_buffer *ring,
return 0;
}

static void
static bool
gen6_bsd_ring_get_irq(struct intel_ring_buffer *ring)
{
ring_get_irq(ring, GT_GEN6_BSD_USER_INTERRUPT);
return ring_get_irq(ring, GT_GEN6_BSD_USER_INTERRUPT);
}

static void
gen6_bsd_ring_put_irq(struct intel_ring_buffer *ring)
{
ring_put_irq(ring, GT_GEN6_BSD_USER_INTERRUPT);
ring_put_irq(ring, GT_GEN6_BSD_USER_INTERRUPT);
}

/* ring buffer for Video Codec for Gen6+ */
Expand All @@ -876,16 +882,16 @@ static const struct intel_ring_buffer gen6_bsd_ring = {

/* Blitter support (SandyBridge+) */

static void
static bool
blt_ring_get_irq(struct intel_ring_buffer *ring)
{
ring_get_irq(ring, GT_BLT_USER_INTERRUPT);
return ring_get_irq(ring, GT_BLT_USER_INTERRUPT);
}

static void
blt_ring_put_irq(struct intel_ring_buffer *ring)
{
ring_put_irq(ring, GT_BLT_USER_INTERRUPT);
ring_put_irq(ring, GT_BLT_USER_INTERRUPT);
}


Expand Down
4 changes: 2 additions & 2 deletions drivers/gpu/drm/i915/intel_ringbuffer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -54,8 +54,8 @@ struct intel_ring_buffer {
u32 irq_seqno; /* last seq seem at irq time */
u32 waiting_seqno;
u32 sync_seqno[I915_NUM_RINGS-1];
u32 irq_refcount;
void (*irq_get)(struct intel_ring_buffer *ring);
atomic_t irq_refcount;
bool __must_check (*irq_get)(struct intel_ring_buffer *ring);
void (*irq_put)(struct intel_ring_buffer *ring);

int (*init)(struct intel_ring_buffer *ring);
Expand Down

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