drm/i915: Dumb down the semaphore logic
While I think the previous code is correct, it was hard to follow and
hard to debug. Since we already have a ring abstraction, might as well
use it to handle the semaphore updates and compares.
I don't expect this code to make semaphores better or worse, but you
never know...
v2:
Remove magic per Keith's suggestions.
Ran Daniel's gem_ring_sync_loop test on this.
v3:
Ignored one of Keith's suggestions.
v4:
Removed some bloat per Daniel's recommendation.
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Keith Packard <keithp@keithp.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Keith Packard <keithp@keithp.com>
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index a40f345..0e99589 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -315,79 +315,127 @@
}
static void
-update_semaphore(struct intel_ring_buffer *ring, int i, u32 seqno)
+update_mboxes(struct intel_ring_buffer *ring,
+ u32 seqno,
+ u32 mmio_offset)
{
- struct drm_device *dev = ring->dev;
- struct drm_i915_private *dev_priv = dev->dev_private;
- int id;
-
- /*
- * cs -> 1 = vcs, 0 = bcs
- * vcs -> 1 = bcs, 0 = cs,
- * bcs -> 1 = cs, 0 = vcs.
- */
- id = ring - dev_priv->ring;
- id += 2 - i;
- id %= 3;
-
- intel_ring_emit(ring,
- MI_SEMAPHORE_MBOX |
- MI_SEMAPHORE_REGISTER |
- MI_SEMAPHORE_UPDATE);
+ intel_ring_emit(ring, MI_SEMAPHORE_MBOX |
+ MI_SEMAPHORE_GLOBAL_GTT |
+ MI_SEMAPHORE_REGISTER |
+ MI_SEMAPHORE_UPDATE);
intel_ring_emit(ring, seqno);
- intel_ring_emit(ring,
- RING_SYNC_0(dev_priv->ring[id].mmio_base) + 4*i);
+ intel_ring_emit(ring, mmio_offset);
}
+/**
+ * gen6_add_request - Update the semaphore mailbox registers
+ *
+ * @ring - ring that is adding a request
+ * @seqno - return seqno stuck into the ring
+ *
+ * Update the mailbox registers in the *other* rings with the current seqno.
+ * This acts like a signal in the canonical semaphore.
+ */
static int
gen6_add_request(struct intel_ring_buffer *ring,
- u32 *result)
+ u32 *seqno)
{
- u32 seqno;
+ u32 mbox1_reg;
+ u32 mbox2_reg;
int ret;
ret = intel_ring_begin(ring, 10);
if (ret)
return ret;
- seqno = i915_gem_get_seqno(ring->dev);
- update_semaphore(ring, 0, seqno);
- update_semaphore(ring, 1, seqno);
+ mbox1_reg = ring->signal_mbox[0];
+ mbox2_reg = ring->signal_mbox[1];
+ *seqno = i915_gem_get_seqno(ring->dev);
+
+ update_mboxes(ring, *seqno, mbox1_reg);
+ update_mboxes(ring, *seqno, mbox2_reg);
intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
- intel_ring_emit(ring, seqno);
+ intel_ring_emit(ring, *seqno);
intel_ring_emit(ring, MI_USER_INTERRUPT);
intel_ring_advance(ring);
- *result = seqno;
return 0;
}
-int
-intel_ring_sync(struct intel_ring_buffer *ring,
- struct intel_ring_buffer *to,
+/**
+ * intel_ring_sync - sync the waiter to the signaller on seqno
+ *
+ * @waiter - ring that is waiting
+ * @signaller - ring which has, or will signal
+ * @seqno - seqno which the waiter will block on
+ */
+static int
+intel_ring_sync(struct intel_ring_buffer *waiter,
+ struct intel_ring_buffer *signaller,
+ int ring,
u32 seqno)
{
int ret;
+ u32 dw1 = MI_SEMAPHORE_MBOX |
+ MI_SEMAPHORE_COMPARE |
+ MI_SEMAPHORE_REGISTER;
- ret = intel_ring_begin(ring, 4);
+ ret = intel_ring_begin(waiter, 4);
if (ret)
return ret;
- intel_ring_emit(ring,
- MI_SEMAPHORE_MBOX |
- MI_SEMAPHORE_REGISTER |
- intel_ring_sync_index(ring, to) << 17 |
- MI_SEMAPHORE_COMPARE);
- intel_ring_emit(ring, seqno);
- intel_ring_emit(ring, 0);
- intel_ring_emit(ring, MI_NOOP);
- intel_ring_advance(ring);
+ intel_ring_emit(waiter, dw1 | signaller->semaphore_register[ring]);
+ intel_ring_emit(waiter, seqno);
+ intel_ring_emit(waiter, 0);
+ intel_ring_emit(waiter, MI_NOOP);
+ intel_ring_advance(waiter);
return 0;
}
+/* VCS->RCS (RVSYNC) or BCS->RCS (RBSYNC) */
+int
+render_ring_sync_to(struct intel_ring_buffer *waiter,
+ struct intel_ring_buffer *signaller,
+ u32 seqno)
+{
+ WARN_ON(signaller->semaphore_register[RCS] == MI_SEMAPHORE_SYNC_INVALID);
+ return intel_ring_sync(waiter,
+ signaller,
+ RCS,
+ seqno);
+}
+
+/* RCS->VCS (VRSYNC) or BCS->VCS (VBSYNC) */
+int
+gen6_bsd_ring_sync_to(struct intel_ring_buffer *waiter,
+ struct intel_ring_buffer *signaller,
+ u32 seqno)
+{
+ WARN_ON(signaller->semaphore_register[VCS] == MI_SEMAPHORE_SYNC_INVALID);
+ return intel_ring_sync(waiter,
+ signaller,
+ VCS,
+ seqno);
+}
+
+/* RCS->BCS (BRSYNC) or VCS->BCS (BVSYNC) */
+int
+gen6_blt_ring_sync_to(struct intel_ring_buffer *waiter,
+ struct intel_ring_buffer *signaller,
+ u32 seqno)
+{
+ WARN_ON(signaller->semaphore_register[BCS] == MI_SEMAPHORE_SYNC_INVALID);
+ return intel_ring_sync(waiter,
+ signaller,
+ BCS,
+ seqno);
+}
+
+
+
#define PIPE_CONTROL_FLUSH(ring__, addr__) \
do { \
intel_ring_emit(ring__, GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE | \
@@ -1027,6 +1075,11 @@
.irq_put = render_ring_put_irq,
.dispatch_execbuffer = render_ring_dispatch_execbuffer,
.cleanup = render_ring_cleanup,
+ .sync_to = render_ring_sync_to,
+ .semaphore_register = {MI_SEMAPHORE_SYNC_INVALID,
+ MI_SEMAPHORE_SYNC_RV,
+ MI_SEMAPHORE_SYNC_RB},
+ .signal_mbox = {GEN6_VRSYNC, GEN6_BRSYNC},
};
/* ring buffer for bit-stream decoder */
@@ -1154,6 +1207,11 @@
.irq_get = gen6_bsd_ring_get_irq,
.irq_put = gen6_bsd_ring_put_irq,
.dispatch_execbuffer = gen6_ring_dispatch_execbuffer,
+ .sync_to = gen6_bsd_ring_sync_to,
+ .semaphore_register = {MI_SEMAPHORE_SYNC_VR,
+ MI_SEMAPHORE_SYNC_INVALID,
+ MI_SEMAPHORE_SYNC_VB},
+ .signal_mbox = {GEN6_RVSYNC, GEN6_BVSYNC},
};
/* Blitter support (SandyBridge+) */
@@ -1281,10 +1339,15 @@
.flush = blt_ring_flush,
.add_request = gen6_add_request,
.get_seqno = ring_get_seqno,
- .irq_get = blt_ring_get_irq,
- .irq_put = blt_ring_put_irq,
+ .irq_get = blt_ring_get_irq,
+ .irq_put = blt_ring_put_irq,
.dispatch_execbuffer = gen6_ring_dispatch_execbuffer,
- .cleanup = blt_ring_cleanup,
+ .cleanup = blt_ring_cleanup,
+ .sync_to = gen6_blt_ring_sync_to,
+ .semaphore_register = {MI_SEMAPHORE_SYNC_BR,
+ MI_SEMAPHORE_SYNC_BV,
+ MI_SEMAPHORE_SYNC_INVALID},
+ .signal_mbox = {GEN6_RBSYNC, GEN6_VBSYNC},
};
int intel_init_render_ring_buffer(struct drm_device *dev)