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>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 0b3550f05026..37c2c5009d9a 100644
--- 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);
 		}
 	}