drm/i915: Record space required for breadcrumb emission

In the next patch, we will use deferred breadcrumb emission. That requires
reserving sufficient space in the ringbuffer to emit the breadcrumb, which
first requires us to know how large the breadcrumb is.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-28-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index a626b26..be9e23b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -434,6 +434,7 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
         * away, e.g. because a GPU scheduler has deferred it.
         */
        req->reserved_space = MIN_SPACE_FOR_ADD_REQUEST;
+       GEM_BUG_ON(req->reserved_space < engine->emit_breadcrumb_sz);
 
        if (i915.enable_execlists)
                ret = intel_logical_ring_alloc_request_extras(req);

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 57dba45..8229bae 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1590,6 +1590,8 @@ static int gen8_emit_breadcrumb(struct drm_i915_gem_request *request)
        return intel_logical_ring_advance(request);
 }
 
+static const int gen8_emit_breadcrumb_sz = 6 + WA_TAIL_DWORDS;
+
 static int gen8_emit_breadcrumb_render(struct drm_i915_gem_request *request)
 {
        struct intel_ring *ring = request->ring;
@@ -1621,6 +1623,8 @@ static int gen8_emit_breadcrumb_render(struct drm_i915_gem_request *request)
        return intel_logical_ring_advance(request);
 }
 
+static const int gen8_emit_breadcrumb_render_sz = 8 + WA_TAIL_DWORDS;
+
 static int gen8_init_rcs_context(struct drm_i915_gem_request *req)
 {
        int ret;
@@ -1695,6 +1699,7 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
        engine->reset_hw = reset_common_ring;
        engine->emit_flush = gen8_emit_flush;
        engine->emit_breadcrumb = gen8_emit_breadcrumb;
+       engine->emit_breadcrumb_sz = gen8_emit_breadcrumb_sz;
        engine->submit_request = execlists_submit_request;
 
        engine->irq_enable = gen8_logical_ring_enable_irq;
@@ -1817,6 +1822,7 @@ int logical_render_ring_init(struct intel_engine_cs *engine)
        engine->init_context = gen8_init_rcs_context;
        engine->emit_flush = gen8_emit_flush_render;
        engine->emit_breadcrumb = gen8_emit_breadcrumb_render;
+       engine->emit_breadcrumb_sz = gen8_emit_breadcrumb_render_sz;
 
        ret = intel_engine_create_scratch(engine, 4096);
        if (ret)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 54c3981..ae9cf6b 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1348,6 +1348,8 @@ static int i9xx_emit_breadcrumb(struct drm_i915_gem_request *req)
        return 0;
 }
 
+static const int i9xx_emit_breadcrumb_sz = 4;
+
 /**
  * gen6_sema_emit_breadcrumb - Update the semaphore mailbox registers
  *
@@ -1401,6 +1403,8 @@ static int gen8_render_emit_breadcrumb(struct drm_i915_gem_request *req)
        return 0;
 }
 
+static const int gen8_render_emit_breadcrumb_sz = 8;
+
 /**
  * intel_ring_sync - sync the waiter to the signaller on seqno
  *
@@ -2638,8 +2642,21 @@ static void intel_ring_default_vfuncs(struct drm_i915_private *dev_priv,
        engine->reset_hw = reset_ring_common;
 
        engine->emit_breadcrumb = i9xx_emit_breadcrumb;
-       if (i915.semaphores)
+       engine->emit_breadcrumb_sz = i9xx_emit_breadcrumb_sz;
+       if (i915.semaphores) {
+               int num_rings;
+
                engine->emit_breadcrumb = gen6_sema_emit_breadcrumb;
+
+               num_rings = hweight32(INTEL_INFO(dev_priv)->ring_mask) - 1;
+               if (INTEL_GEN(dev_priv) >= 8) {
+                       engine->emit_breadcrumb_sz += num_rings * 6;
+               } else {
+                       engine->emit_breadcrumb_sz += num_rings * 3;
+                       if (num_rings & 1)
+                               engine->emit_breadcrumb_sz++;
+               }
+       }
        engine->submit_request = i9xx_submit_request;
 
        if (INTEL_GEN(dev_priv) >= 8)
@@ -2667,9 +2684,17 @@ int intel_init_render_ring_buffer(struct intel_engine_cs *engine)
        if (INTEL_GEN(dev_priv) >= 8) {
                engine->init_context = intel_rcs_ctx_init;
                engine->emit_breadcrumb = gen8_render_emit_breadcrumb;
+               engine->emit_breadcrumb_sz = gen8_render_emit_breadcrumb_sz;
                engine->emit_flush = gen8_render_ring_flush;
-               if (i915.semaphores)
+               if (i915.semaphores) {
+                       int num_rings;
+
                        engine->semaphore.signal = gen8_rcs_signal;
+
+                       num_rings =
+                               hweight32(INTEL_INFO(dev_priv)->ring_mask) - 1;
+                       engine->emit_breadcrumb_sz += num_rings * 6;
+               }
        } else if (INTEL_GEN(dev_priv) >= 6) {
                engine->init_context = intel_rcs_ctx_init;
                engine->emit_flush = gen7_render_ring_flush;

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index a5ced16..7b7aaaf 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -256,6 +256,7 @@ struct intel_engine_cs {
 #define I915_DISPATCH_PINNED BIT(1)
 #define I915_DISPATCH_RS     BIT(2)
        int             (*emit_breadcrumb)(struct drm_i915_gem_request *req);
+       int             emit_breadcrumb_sz;
 
        /* Pass the request to the hardware queue (e.g. directly into
         * the legacy ringbuffer or to the end of an execlist).