drm/i915: Add has_64k_pages flag

Add a new platform flag, has_64k_pages, to mark the requirement of 64K
GTT page sizes or larger for device local memory access.

Also implies that we require or at least support the compact PT layout
for the ppGTT when using 64K GTT pages.

v2: More explanation for the flag [Thomas]

Signed-off-by: Stuart Summers <[e-mail]>
Signed-off-by: Ramalingam C <[e-mail]>
Reviewed-by: Lucas De Marchi <[e-mail]>
Reviewed-by: Andi Shyti <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/i915/i915_drv.h

···
 #define HAS_MSLICES(dev_priv) \
 	(INTEL_INFO(dev_priv)->has_mslices)
 
+/*
+ * Set this flag, when platform requires 64K GTT page sizes or larger for
+ * device local memory access. Also this flag implies that we require or
+ * at least support the compact PT layout for the ppGTT when using the 64K
+ * GTT pages.
+ */
+#define HAS_64K_PAGES(dev_priv) (INTEL_INFO(dev_priv)->has_64k_pages)
+
 #define HAS_IPC(dev_priv)		 (INTEL_INFO(dev_priv)->display.has_ipc)
 
 #define HAS_REGION(i915, i) (INTEL_INFO(i915)->memory_regions & (i))

drivers/gpu/drm/i915/i915_pci.c

···
 	DGFX_FEATURES,
 	PLATFORM(INTEL_XEHPSDV),
 	.display = { },
+	.has_64k_pages = 1,
 	.pipe_mask = 0,
 	.platform_engine_mask =
 		BIT(RCS0) | BIT(BCS0) |
···
 	.graphics.rel = 55,
 	.media.rel = 55,
 	PLATFORM(INTEL_DG2),
+	.has_64k_pages = 1,
 	.platform_engine_mask =
 		BIT(RCS0) | BIT(BCS0) |
 		BIT(VECS0) | BIT(VECS1) |

drivers/gpu/drm/i915/intel_device_info.h

···
 	func(is_dgfx); \
 	/* Keep has_* in alphabetical order */ \
 	func(has_64bit_reloc); \
+	func(has_64k_pages); \
 	func(gpu_reset_clobbers_display); \
 	func(has_reset_engine); \
 	func(has_global_mocs); \