[Intel-gfx] [PATCH 2/4] drm/i915/gt: Use caller provided forcewake for intel_mocs_init_engine

[Chris Wilson]

During post-reset resume, we call intel_mocs_init_engine to reinitialise
the MOCS registers. Suprisingly, especially when enhanced by lockdep,
the acquisition of the forcewake lock around each register write takes a
substantial portion of the reset time. We don't need to use the
individual forcewake here as we can assume that the caller is holding a
blanket forcewake for the reset&resume and the resume is serialised.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/gt/intel_mocs.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_mocs.c b/drivers/gpu/drm/i915/gt/intel_mocs.c
index ae6cbf0d517c..290a5e9b90b9 100644
--- a/drivers/gpu/drm/i915/gt/intel_mocs.c
+++ b/drivers/gpu/drm/i915/gt/intel_mocs.c
@@ -346,6 +346,9 @@ void intel_mocs_init_engine(struct intel_engine_cs *engine)
 	unsigned int index;
 	u32 unused_value;
 
+	/* Called under a blanket forcewake */
+	assert_forcewakes_active(uncore, FORCEWAKE_ALL);
+
 	if (!get_mocs_settings(gt, &table))
 		return;
 
@@ -355,16 +358,16 @@ void intel_mocs_init_engine(struct intel_engine_cs *engine)
 	for (index = 0; index < table.size; index++) {
 		u32 value = get_entry_control(&table, index);
 
-		intel_uncore_write(uncore,
-				   mocs_register(engine->id, index),
-				   value);
+		intel_uncore_write_fw(uncore,
+				      mocs_register(engine->id, index),
+				      value);
 	}
 
 	/* All remaining entries are also unused */
 	for (; index < table.n_entries; index++)
-		intel_uncore_write(uncore,
-				   mocs_register(engine->id, index),
-				   unused_value);
+		intel_uncore_write_fw(uncore,
+				      mocs_register(engine->id, index),
+				      unused_value);
 }
 
 /**
-- 
2.20.1