drm/i915: Do not call API requiring struct_mutex where it is not available

LRC code was calling GEM API like i915_gem_obj_ggtt_offset from
places where the struct_mutex cannot be grabbed (irq handlers).

To avoid that this patch caches some interesting bits and values
in the engine and context structures.

Some usages are also removed where they are not needed like a
few asserts which are either impossible or have been checked
already during engine initialization.

Side benefit is also that interrupt handlers and command
submission stop evaluating invariant conditionals, like what
Gen we are running on, on every interrupt and every command
submitted.

This patch deals with logical ring context id and descriptors
while subsequent patches will deal with the remaining issues.

v2:
 * Cache the VMA instead of the address. (Chris Wilson)
 * Incorporate Dave Gordon's good comments and function name.

v3:
 * Extract ctx descriptor template to a function and group
   functions dealing with ctx descriptor & co together near
   top of the file. (Dave Gordon)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Gordon <david.s.gordon@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452870629-13830-1-git-send-email-tvrtko.ursulin@linux.intel.com

1 files changed, 6 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index e3377abc0d4d..0b3550f05026 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1994,12 +1994,13 @@ static int i915_context_status(struct seq_file *m, void *unused)
 }
 
 static void i915_dump_lrc_obj(struct seq_file *m,
-			      struct intel_engine_cs *ring,
-			      struct drm_i915_gem_object *ctx_obj)
+			      struct intel_context *ctx,
+			      struct intel_engine_cs *ring)
 {
 	struct page *page;
 	uint32_t *reg_state;
 	int j;
+	struct drm_i915_gem_object *ctx_obj = ctx->engine[ring->id].state;
 	unsigned long ggtt_offset = 0;
 
 	if (ctx_obj == NULL) {
@@ -2009,7 +2010,7 @@ static void i915_dump_lrc_obj(struct seq_file *m,
 	}
 
 	seq_printf(m, "CONTEXT: %s %u\n", ring->name,
-		   intel_execlists_ctx_id(ctx_obj));
+		   intel_execlists_ctx_id(ctx, ring));
 
 	if (!i915_gem_obj_ggtt_bound(ctx_obj))
 		seq_puts(m, "\tNot bound in GGTT\n");
@@ -2058,8 +2059,7 @@ 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)
-				i915_dump_lrc_obj(m, ring,
-						  ctx->engine[i].state);
+				i915_dump_lrc_obj(m, ctx, ring);
 		}
 	}
 
@@ -2133,11 +2133,8 @@ static int i915_execlists(struct seq_file *m, void *data)
 
 		seq_printf(m, "\t%d requests in queue\n", count);
 		if (head_req) {
-			struct drm_i915_gem_object *ctx_obj;
-
-			ctx_obj = head_req->ctx->engine[ring_id].state;
 			seq_printf(m, "\tHead request id: %u\n",
-				   intel_execlists_ctx_id(ctx_obj));
+				   intel_execlists_ctx_id(head_req->ctx, ring));
 			seq_printf(m, "\tHead request tail: %u\n",
 				   head_req->tail);
 		}