drm/i915: abolish separate per-ring default_context pointers

Now that we've eliminated a lot of uses of ring->default_context,
we can eliminate the pointer itself.

All the engines share the same default intel_context, so we can just
keep a single reference to it in the dev_priv structure rather than one
in each of the engine[] elements. This make refcounting more sensible
too, as we now have a refcount of one for the one pointer, rather than
a refcount of one but multiple pointers.

From an idea by Chris Wilson.

v2:	transform an extra instance of ring->default_context introduced by
    42f1cae8c drm/i915: Restore inhibiting the load of the default context
    That patch's commentary includes:
	v2: Mark the global default context as uninitialized on GPU reset so
	    that the context-local workarounds are reloaded upon re-enabling
    The code implementing that now also benefits from the replacement of
    the multiple (per-ring) pointers to the default context with a single
    pointer to the unique kernel context.

v4:	Rebased, remove underused local (Nick Hoath)

Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Reviewed-by: Nick Hoath <nicholas.hoath@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1453230175-19330-3-git-send-email-david.s.gordon@intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 0b3550f050262265d68d971d1279f53889d741aa..37c2c5009d9a928ae5bc0c03353d5540b6553a66 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1961,7 +1961,7 @@ static int i915_context_status(struct seq_file *m, void *unused)
                seq_puts(m, "HW context ");
                describe_ctx(m, ctx);
                for_each_ring(ring, dev_priv, i) {
-                       if (ring->default_context == ctx)
+                       if (dev_priv->kernel_context == ctx)
                                seq_printf(m, "(default context %s) ",
                                           ring->name);
                }
@@ -2058,7 +2058,7 @@ static int i915_dump_lrc(struct seq_file *m, void *unused)
 
        list_for_each_entry(ctx, &dev_priv->context_list, link) {
                for_each_ring(ring, dev_priv, i) {
-                       if (ring->default_context != ctx)
+                       if (dev_priv->kernel_context != ctx)
                                i915_dump_lrc_obj(m, ctx, ring);
                }
        }

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 125659488756c5daba0eb2c2455b6fad0c36335b..840368de3f4ff763b0c74e6fbda5aedf263c9be7 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1948,6 +1948,8 @@ struct drm_i915_private {
                void (*stop_ring)(struct intel_engine_cs *ring);
        } gt;
 
+       struct intel_context *kernel_context;
+
        bool edp_low_vswing;
 
        /* perform PHY state sanity checks? */

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 8e716b6b5d59a98cf3f6a9fe1e39f1d8a8cab792..06abe1bf5afc7b0e34d94c3e9ce1f6fc07b4c7ae 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2680,7 +2680,7 @@ void i915_gem_request_free(struct kref *req_ref)
 
        if (ctx) {
                if (i915.enable_execlists) {
-                       if (ctx != req->ring->default_context)
+                       if (ctx != req->i915->kernel_context)
                                intel_lr_context_unpin(req);
                }
 
@@ -2776,7 +2776,7 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
        int err;
 
        if (ctx == NULL)
-               ctx = engine->default_context;
+               ctx = to_i915(engine->dev)->kernel_context;
        err = __i915_gem_request_alloc(engine, ctx, &req);
        return err ? ERR_PTR(err) : req;
 }
@@ -4864,7 +4864,7 @@ i915_gem_init_hw(struct drm_device *dev)
         */
        init_unused_rings(dev);
 
-       BUG_ON(!dev_priv->ring[RCS].default_context);
+       BUG_ON(!dev_priv->kernel_context);
 
        ret = i915_ppgtt_init_hw(dev);
        if (ret) {

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index c25083c78ba7c21c7cdc92ed43f62c7e499851bb..6a4f64b03db65114962b459c5d6dd69e7c1d569b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -347,22 +347,20 @@ void i915_gem_context_reset(struct drm_device *dev)
                        i915_gem_context_unreference(lctx);
                        ring->last_context = NULL;
                }
-
-               /* Force the GPU state to be reinitialised on enabling */
-               if (ring->default_context)
-                       ring->default_context->legacy_hw_ctx.initialized = false;
        }
+
+       /* Force the GPU state to be reinitialised on enabling */
+       dev_priv->kernel_context->legacy_hw_ctx.initialized = false;
 }
 
 int i915_gem_context_init(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_context *ctx;
-       int i;
 
        /* Init should only be called once per module load. Eventually the
         * restriction on the context_disabled check can be loosened. */
-       if (WARN_ON(dev_priv->ring[RCS].default_context))
+       if (WARN_ON(dev_priv->kernel_context))
                return 0;
 
        if (intel_vgpu_active(dev) && HAS_LOGICAL_RING_CONTEXTS(dev)) {
@@ -392,12 +390,7 @@ int i915_gem_context_init(struct drm_device *dev)
                return PTR_ERR(ctx);
        }
 
-       for (i = 0; i < I915_NUM_RINGS; i++) {
-               struct intel_engine_cs *ring = &dev_priv->ring[i];
-
-               /* NB: RCS will hold a ref for all rings */
-               ring->default_context = ctx;
-       }
+       dev_priv->kernel_context = ctx;
 
        DRM_DEBUG_DRIVER("%s context support initialized\n",
                        i915.enable_execlists ? "LR" :
@@ -408,7 +401,7 @@ int i915_gem_context_init(struct drm_device *dev)
 void i915_gem_context_fini(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
-       struct intel_context *dctx = dev_priv->ring[RCS].default_context;
+       struct intel_context *dctx = dev_priv->kernel_context;
        int i;
 
        if (dctx->legacy_hw_ctx.rcs_state) {
@@ -435,17 +428,17 @@ void i915_gem_context_fini(struct drm_device *dev)
                i915_gem_object_ggtt_unpin(dctx->legacy_hw_ctx.rcs_state);
        }
 
-       for (i = 0; i < I915_NUM_RINGS; i++) {
+       for (i = I915_NUM_RINGS; --i >= 0;) {
                struct intel_engine_cs *ring = &dev_priv->ring[i];
 
-               if (ring->last_context)
+               if (ring->last_context) {
                        i915_gem_context_unreference(ring->last_context);
-
-               ring->default_context = NULL;
-               ring->last_context = NULL;
+                       ring->last_context = NULL;
+               }
        }
 
        i915_gem_context_unreference(dctx);
+       dev_priv->kernel_context = NULL;
 }
 
 int i915_gem_context_enable(struct drm_i915_gem_request *req)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 06ca4082735bc84c4ff5073bf60fb303096fce08..7eeb24427785430aa3794808d3961374fe55fc95 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1050,7 +1050,7 @@ static void i915_gem_record_rings(struct drm_device *dev,
                        if (request)
                                rbuf = request->ctx->engine[ring->id].ringbuf;
                        else
-                               rbuf = ring->default_context->engine[ring->id].ringbuf;
+                               rbuf = dev_priv->kernel_context->engine[ring->id].ringbuf;
                } else
                        rbuf = ring->buffer;
 

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 9c244247c13e879bb3a5c0918a4319c03f4bdc36..51ae5c1f806ddc46c945614c1d0922de4a3011ed 100644 (file)
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -964,7 +964,7 @@ int i915_guc_submission_enable(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_guc *guc = &dev_priv->guc;
-       struct intel_context *ctx = dev_priv->ring[RCS].default_context;
+       struct intel_context *ctx = dev_priv->kernel_context;
        struct i915_guc_client *client;
 
        /* client for execbuf submission */
@@ -1021,7 +1021,7 @@ int intel_guc_suspend(struct drm_device *dev)
        if (!i915.enable_guc_submission)
                return 0;
 
-       ctx = dev_priv->ring[RCS].default_context;
+       ctx = dev_priv->kernel_context;
 
        data[0] = HOST2GUC_ACTION_ENTER_S_STATE;
        /* any value greater than GUC_POWER_D0 */
@@ -1047,7 +1047,7 @@ int intel_guc_resume(struct drm_device *dev)
        if (!i915.enable_guc_submission)
                return 0;
 
-       ctx = dev_priv->ring[RCS].default_context;
+       ctx = dev_priv->kernel_context;
 
        data[0] = HOST2GUC_ACTION_EXIT_S_STATE;
        data[1] = GUC_POWER_D0;

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index ec2482daffa6e57447464e0e4bd552e9e2f5e7aa..2c6da4013b1a932d9d8d212e7bcb0124eed2b551 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -598,7 +598,7 @@ static int execlists_context_queue(struct drm_i915_gem_request *request)
        struct drm_i915_gem_request *cursor;
        int num_elements = 0;
 
-       if (request->ctx != ring->default_context)
+       if (request->ctx != request->i915->kernel_context)
                intel_lr_context_pin(request);
 
        i915_gem_request_reference(request);
@@ -690,7 +690,7 @@ int intel_logical_ring_alloc_request_extras(struct drm_i915_gem_request *request
 
        request->ringbuf = request->ctx->engine[request->ring->id].ringbuf;
 
-       if (request->ctx != request->ring->default_context) {
+       if (request->ctx != request->i915->kernel_context) {
                ret = intel_lr_context_pin(request);
                if (ret)
                        return ret;
@@ -1006,7 +1006,7 @@ void intel_execlists_retire_requests(struct intel_engine_cs *ring)
                struct drm_i915_gem_object *ctx_obj =
                                ctx->engine[ring->id].state;
 
-               if (ctx_obj && (ctx != ring->default_context))
+               if (ctx_obj && (ctx != req->i915->kernel_context))
                        intel_lr_context_unpin(req);
                list_del(&req->execlist_link);
                i915_gem_request_unreference(req);
@@ -1529,7 +1529,7 @@ static int gen8_init_common_ring(struct intel_engine_cs *ring)
        u8 next_context_status_buffer_hw;
 
        lrc_setup_hardware_status_page(ring,
-                               ring->default_context->engine[ring->id].state);
+                               dev_priv->kernel_context->engine[ring->id].state);
 
        I915_WRITE_IMR(ring, ~(ring->irq_enable_mask | ring->irq_keep_mask));
        I915_WRITE(RING_HWSTAM(ring->mmio_base), 0xffffffff);
@@ -2005,6 +2005,7 @@ logical_ring_default_irqs(struct intel_engine_cs *ring, unsigned shift)
 static int
 logical_ring_init(struct drm_device *dev, struct intel_engine_cs *ring)
 {
+       struct intel_context *dctx = to_i915(dev)->kernel_context;
        int ret;
 
        /* Intentionally left blank. */
@@ -2027,12 +2028,12 @@ logical_ring_init(struct drm_device *dev, struct intel_engine_cs *ring)
        if (ret)
                goto error;
 
-       ret = intel_lr_context_deferred_alloc(ring->default_context, ring);
+       ret = intel_lr_context_deferred_alloc(dctx, ring);
        if (ret)
                goto error;
 
        /* As this is the default context, always pin it */
-       ret = intel_lr_context_do_pin(ring, ring->default_context);
+       ret = intel_lr_context_do_pin(ring, dctx);
        if (ret) {
                DRM_ERROR(
                        "Failed to pin and map ringbuffer %s: %d\n",
@@ -2398,7 +2399,7 @@ void intel_lr_context_free(struct intel_context *ctx)
                                        ctx->engine[i].ringbuf;
                        struct intel_engine_cs *ring = ringbuf->ring;
 
-                       if (ctx == ring->default_context) {
+                       if (ctx == ctx->i915->kernel_context) {
                                intel_unpin_ringbuffer_obj(ringbuf);
                                i915_gem_object_ggtt_unpin(ctx_obj);
                        }
@@ -2517,7 +2518,7 @@ int intel_lr_context_deferred_alloc(struct intel_context *ctx,
        ctx->engine[ring->id].ringbuf = ringbuf;
        ctx->engine[ring->id].state = ctx_obj;
 
-       if (ctx != ring->default_context && ring->init_context) {
+       if (ctx != ctx->i915->kernel_context && ring->init_context) {
                struct drm_i915_gem_request *req;
 
                req = i915_gem_request_alloc(ring, ctx);

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 91ac8a9bd9038bee3c13a405397a0b3426df735e..0014fcaa5a0c179458d36d0669c7ebf796a1cff0 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -309,7 +309,6 @@ struct  intel_engine_cs {
 
        wait_queue_head_t irq_queue;
 
-       struct intel_context *default_context;
        struct intel_context *last_context;
 
        struct intel_ring_hangcheck hangcheck;