drm/i915: Split out !RCS legacy context switching

Having the !RCS legacy context switch threaded through the RCS switching
code makes it much harder to follow and understand. In the next patch, I
want to fix a bug handling the incomplete switch, this is made much
simpler if we segregate the two paths now.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1460565315-7748-14-git-send-email-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 453b655e86fc3d6e78334e68549e2170c84fe765..c027240aacf3a0fea70bbdd7b098eeee6b483ce0 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -609,9 +609,9 @@ mi_set_context(struct drm_i915_gem_request *req, u32 hw_flags)
        return ret;
 }
 
-static inline bool should_skip_switch(struct intel_engine_cs *engine,
-                                     struct intel_context *from,
-                                     struct intel_context *to)
+static inline bool skip_rcs_switch(struct intel_engine_cs *engine,
+                                  struct intel_context *from,
+                                  struct intel_context *to)
 {
        if (to->remap_slice)
                return false;
@@ -626,15 +626,17 @@ static inline bool should_skip_switch(struct intel_engine_cs *engine,
 static bool
 needs_pd_load_pre(struct intel_engine_cs *engine, struct intel_context *to)
 {
-       struct drm_i915_private *dev_priv = engine->dev->dev_private;
-
        if (!to->ppgtt)
                return false;
 
-       if (INTEL_INFO(engine->dev)->gen < 8)
+       if (engine->last_context == to &&
+           !(intel_engine_flag(engine) & to->ppgtt->pd_dirty_rings))
+               return false;
+
+       if (engine->id != RCS)
                return true;
 
-       if (engine != &dev_priv->engine[RCS])
+       if (INTEL_INFO(engine->dev)->gen < 8)
                return true;
 
        return false;
@@ -661,32 +663,24 @@ needs_pd_load_post(struct intel_engine_cs *engine, struct intel_context *to,
        return false;
 }
 
-static int do_switch(struct drm_i915_gem_request *req)
+static int do_rcs_switch(struct drm_i915_gem_request *req)
 {
        struct intel_context *to = req->ctx;
        struct intel_engine_cs *engine = req->engine;
-       struct drm_i915_private *dev_priv = req->i915;
        struct intel_context *from = engine->last_context;
        u32 hw_flags = 0;
        bool uninitialized = false;
        int ret, i;
 
-       if (from != NULL && engine == &dev_priv->engine[RCS]) {
-               BUG_ON(from->legacy_hw_ctx.rcs_state == NULL);
-               BUG_ON(!i915_gem_obj_is_pinned(from->legacy_hw_ctx.rcs_state));
-       }
-
-       if (should_skip_switch(engine, from, to))
+       if (skip_rcs_switch(engine, from, to))
                return 0;
 
        /* Trying to pin first makes error handling easier. */
-       if (engine == &dev_priv->engine[RCS]) {
-               ret = i915_gem_obj_ggtt_pin(to->legacy_hw_ctx.rcs_state,
-                                           get_context_alignment(engine->dev),
-                                           0);
-               if (ret)
-                       return ret;
-       }
+       ret = i915_gem_obj_ggtt_pin(to->legacy_hw_ctx.rcs_state,
+                                   get_context_alignment(engine->dev),
+                                   0);
+       if (ret)
+               return ret;
 
        /*
         * Pin can switch back to the default context if we end up calling into
@@ -709,12 +703,6 @@ static int do_switch(struct drm_i915_gem_request *req)
                to->ppgtt->pd_dirty_rings &= ~intel_engine_flag(engine);
        }
 
-       if (engine != &dev_priv->engine[RCS]) {
-               if (from)
-                       i915_gem_context_unreference(from);
-               goto done;
-       }
-
        /*
         * Clear this page out of any CPU caches for coherent swap-in/out. Note
         * that thanks to write = false in this call and us not setting any gpu
@@ -802,7 +790,6 @@ static int do_switch(struct drm_i915_gem_request *req)
        uninitialized = !to->legacy_hw_ctx.initialized;
        to->legacy_hw_ctx.initialized = true;
 
-done:
        i915_gem_context_reference(to);
        engine->last_context = to;
 
@@ -817,8 +804,7 @@ done:
        return 0;
 
 unpin_out:
-       if (engine->id == RCS)
-               i915_gem_object_ggtt_unpin(to->legacy_hw_ctx.rcs_state);
+       i915_gem_object_ggtt_unpin(to->legacy_hw_ctx.rcs_state);
        return ret;
 }
 
@@ -843,17 +829,33 @@ int i915_switch_context(struct drm_i915_gem_request *req)
        WARN_ON(i915.enable_execlists);
        WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
 
-       if (req->ctx->legacy_hw_ctx.rcs_state == NULL) { /* We have the fake context */
-               if (req->ctx != engine->last_context) {
-                       i915_gem_context_reference(req->ctx);
+       if (engine->id != RCS ||
+           req->ctx->legacy_hw_ctx.rcs_state == NULL) {
+               struct intel_context *to = req->ctx;
+
+               if (needs_pd_load_pre(engine, to)) {
+                       int ret;
+
+                       trace_switch_mm(engine, to);
+                       ret = to->ppgtt->switch_mm(to->ppgtt, req);
+                       if (ret)
+                               return ret;
+
+                       /* Doing a PD load always reloads the page dirs */
+                       to->ppgtt->pd_dirty_rings &= ~intel_engine_flag(engine);
+               }
+
+               if (to != engine->last_context) {
+                       i915_gem_context_reference(to);
                        if (engine->last_context)
                                i915_gem_context_unreference(engine->last_context);
-                       engine->last_context = req->ctx;
+                       engine->last_context = to;
                }
+
                return 0;
        }
 
-       return do_switch(req);
+       return do_rcs_switch(req);
 }
 
 static bool contexts_enabled(struct drm_device *dev)