[v10] drm/i915: Allocate intel_engine_cs structure only for the enabled engines

From: Akash Goel <akash.goel@intel.com>

From: Akash Goel <akash.goel@intel.com>

With the possibility of addition of many more number of rings in future,
the drm_i915_private structure could bloat as an array, of type
intel_engine_cs, is embedded inside it.
	struct intel_engine_cs engine[I915_NUM_ENGINES];
Though this is still fine as generally there is only a single instance of
drm_i915_private structure used, but not all of the possible rings would be
enabled or active on most of the platforms. Some memory can be saved by
allocating intel_engine_cs structure only for the enabled/active engines.
Currently the engine/ring ID is kept static and dev_priv->engine[] is simply
indexed using the enums defined in intel_engine_id.
To save memory and continue using the static engine/ring IDs, 'engine' is
defined as an array of pointers.
	struct intel_engine_cs *engine[I915_NUM_ENGINES];
dev_priv->engine[engine_ID] will be NULL for disabled engine instances.

There is a text size reduction of 928 bytes, from 1028200 to 1027272, for
i915.o file (but for i915.ko file text size remain same as 1193131 bytes).

v2:
- Remove the engine iterator field added in drm_i915_private structure,
  instead pass a local iterator variable to the for_each_engine**
  macros. (Chris)
- Do away with intel_engine_initialized() and instead directly use the
  NULL pointer check on engine pointer. (Chris)

v3:
- Remove for_each_engine_id() macro, as the updated macro for_each_engine()
  can be used in place of it. (Chris)
- Protect the access to Render engine Fault register with a NULL check, as
  engine specific init is done later in Driver load sequence.

v4:
- Use !!dev_priv->engine[VCS] style for the engine check in getparam. (Chris)
- Kill the superfluous init_engine_lists().

v5:
- Cleanup the intel_engines_init() & intel_engines_setup(), with respect to
  allocation of intel_engine_cs structure. (Chris)

v6:
- Rebase.

v7:
- Optimize the for_each_engine_masked() macro. (Chris)
- Change the type of 'iter' local variable to enum intel_engine_id. (Chris)
- Rebase.

v8: Rebase.

v9: Rebase.

v10:
- For index calculation use engine ID instead of pointer based arithmetic in
  intel_engine_sync_index() as engine pointers are not contiguous now (Chris)
- For appropriateness, rename local enum variable 'iter' to 'id'. (Joonas)
- Use for_each_engine macro for cleanup in intel_engines_init() and remove
  check for NULL engine pointer in cleanup() routines. (Joonas)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Akash Goel <akash.goel@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_cmd_parser.c     |  3 +-
 drivers/gpu/drm/i915/i915_debugfs.c        | 57 ++++++++++++++++++------------
 drivers/gpu/drm/i915/i915_drv.c            | 11 +++---
 drivers/gpu/drm/i915/i915_drv.h            | 22 ++++--------
 drivers/gpu/drm/i915/i915_gem.c            | 29 +++++++--------
 drivers/gpu/drm/i915/i915_gem_context.c    | 15 ++++----
 drivers/gpu/drm/i915/i915_gem_evict.c      |  3 +-
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |  6 ++--
 drivers/gpu/drm/i915/i915_gem_gtt.c        | 14 +++++---
 drivers/gpu/drm/i915/i915_gem_request.c    |  5 +--
 drivers/gpu/drm/i915/i915_gpu_error.c      | 30 ++++++++--------
 drivers/gpu/drm/i915/i915_guc_submission.c | 12 ++++---
 drivers/gpu/drm/i915/i915_irq.c            | 44 ++++++++++++-----------
 drivers/gpu/drm/i915/intel_breadcrumbs.c   |  6 ++--
 drivers/gpu/drm/i915/intel_display.c       |  8 ++---
 drivers/gpu/drm/i915/intel_engine_cs.c     | 26 ++++++++++----
 drivers/gpu/drm/i915/intel_guc_loader.c    |  6 ++--
 drivers/gpu/drm/i915/intel_lrc.c           | 11 +++---
 drivers/gpu/drm/i915/intel_overlay.c       |  2 +-
 drivers/gpu/drm/i915/intel_pm.c            | 17 +++++----
 drivers/gpu/drm/i915/intel_ringbuffer.c    | 15 ++++----
 drivers/gpu/drm/i915/intel_ringbuffer.h    |  8 +----
 22 files changed, 193 insertions(+), 157 deletions(-)

[v10] drm/i915: Allocate intel_engine_cs structure only for the enabled engines

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