drm/i915/gt: rename legacy engine->hw_id to engine->gen6_hw_id

We kept adding new engines and for that increasing hw_id unnecessarily:
it's not used since GRAPHICS_VER == 8. Prepend "gen6" to the field and
try to pack it in the structs to give a hint this field is actually not
used in recent platforms.
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210720232014.3302645-4-lucas.demarchi@intel.com

drivers/gpu/drm/i915/gt/intel_engine_cs.c

@@ -42,7 +42,7 @@
 
 #define MAX_MMIO_BASES 3
 struct engine_info {
-	unsigned int hw_id;
+	u8 gen6_hw_id;
 	u8 class;
 	u8 instance;
 	/* mmio bases table *must* be sorted in reverse graphics_ver order */
@@ -54,7 +54,7 @@ struct engine_info {
 
 static const struct engine_info intel_engines[] = {
 	[RCS0] = {
-		.hw_id = RCS0_HW,
+		.gen6_hw_id = RCS0_HW,
 		.class = RENDER_CLASS,
 		.instance = 0,
 		.mmio_bases = {
@@ -62,7 +62,7 @@ static const struct engine_info intel_engines[] = {
 		},
 	},
 	[BCS0] = {
-		.hw_id = BCS0_HW,
+		.gen6_hw_id = BCS0_HW,
 		.class = COPY_ENGINE_CLASS,
 		.instance = 0,
 		.mmio_bases = {
@@ -70,7 +70,7 @@ static const struct engine_info intel_engines[] = {
 		},
 	},
 	[VCS0] = {
-		.hw_id = VCS0_HW,
+		.gen6_hw_id = VCS0_HW,
 		.class = VIDEO_DECODE_CLASS,
 		.instance = 0,
 		.mmio_bases = {
@@ -102,7 +102,7 @@ static const struct engine_info intel_engines[] = {
 		},
 	},
 	[VECS0] = {
-		.hw_id = VECS0_HW,
+		.gen6_hw_id = VECS0_HW,
 		.class = VIDEO_ENHANCEMENT_CLASS,
 		.instance = 0,
 		.mmio_bases = {
@@ -290,7 +290,7 @@ static int intel_engine_setup(struct intel_gt *gt, enum intel_engine_id id)
 	engine->i915 = i915;
 	engine->gt = gt;
 	engine->uncore = gt->uncore;
-	engine->hw_id = info->hw_id;
+	engine->gen6_hw_id = info->gen6_hw_id;
 	guc_class = engine_class_to_guc_class(info->class);
 	engine->guc_id = MAKE_GUC_ID(guc_class, info->instance);
 	engine->mmio_base = __engine_mmio_base(i915, info->mmio_bases);

drivers/gpu/drm/i915/gt/intel_engine_types.h

@@ -264,11 +264,11 @@ struct intel_engine_cs {
 	enum intel_engine_id id;
 	enum intel_engine_id legacy_idx;
 
-	unsigned int hw_id;
 	unsigned int guc_id;
 
 	intel_engine_mask_t mask;
 
+	u8 gen6_hw_id;
 	u8 class;
 	u8 instance;
 

drivers/gpu/drm/i915/i915_reg.h

@@ -2572,7 +2572,7 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define   ARB_MODE_BWGTLB_DISABLE (1 << 9)
 #define   ARB_MODE_SWIZZLE_BDW	(1 << 1)
 #define RENDER_HWS_PGA_GEN7	_MMIO(0x04080)
-#define RING_FAULT_REG(engine)	_MMIO(0x4094 + 0x100 * (engine)->hw_id)
+#define RING_FAULT_REG(engine)	_MMIO(0x4094 + 0x100 * (engine)->gen6_hw_id)
 #define GEN8_RING_FAULT_REG	_MMIO(0x4094)
 #define GEN12_RING_FAULT_REG	_MMIO(0xcec4)
 #define   GEN8_RING_FAULT_ENGINE_ID(x)	(((x) >> 12) & 0x7)