drm/i915: Make for_each_engine_masked() more compact and quicker

Rather than walk the full array of engines checking whether each is in
the mask in turn, we can use the mask to jump to the right engines. This
should quicker for a sparse array of engines or mask, whilst generating
smaller code:

   text	   data	    bss	    dec	    hex	filename
1251010	   4579	    800	1256389	 132bc5	drivers/gpu/drm/i915/i915.ko
1250530	   4579	    800	1255909	 1329e5	drivers/gpu/drm/i915/i915.ko

The downside is that we have to pass in a temporary, alas no C99
iterators yet.

[P.S. Joonas doesn't like having to pass extra temporaries into the
macro, and even less that I called them tmp. As yet, we haven't found a
macro that avoids passing in a temporary that is smaller. We probably
will get C99 iterators first!]

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160827075401.16470-2-chris@chris-wilson.co.uk

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 43f833901b8e..e9f68cd56e32 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1597,8 +1597,10 @@ static int gen6_reset_engines(struct drm_i915_private *dev_priv,
 	if (engine_mask == ALL_ENGINES) {
 		hw_mask = GEN6_GRDOM_FULL;
 	} else {
+		unsigned int tmp;
+
 		hw_mask = 0;
-		for_each_engine_masked(engine, dev_priv, engine_mask)
+		for_each_engine_masked(engine, dev_priv, engine_mask, tmp)
 			hw_mask |= hw_engine_mask[engine->id];
 	}
 
@@ -1714,15 +1716,16 @@ static int gen8_reset_engines(struct drm_i915_private *dev_priv,
 			      unsigned engine_mask)
 {
 	struct intel_engine_cs *engine;
+	unsigned int tmp;
 
-	for_each_engine_masked(engine, dev_priv, engine_mask)
+	for_each_engine_masked(engine, dev_priv, engine_mask, tmp)
 		if (gen8_request_engine_reset(engine))
 			goto not_ready;
 
 	return gen6_reset_engines(dev_priv, engine_mask);
 
 not_ready:
-	for_each_engine_masked(engine, dev_priv, engine_mask)
+	for_each_engine_masked(engine, dev_priv, engine_mask, tmp)
 		gen8_unrequest_engine_reset(engine);
 
 	return -EIO;