Commit a50794f2 authored by Ramalingam C's avatar Ramalingam C
Browse files

uapi/drm/i915: Document memory residency and Flat-CCS capability of obj 



Capture the impact of memory region preference list of the objects, on
their memory residency and Flat-CCS capability.

v2:
  Fix the Flat-CCS capability of an obj with {lmem, smem} preference
  list [Thomas]
v3:
  Reworded the doc [Matt]
v4:
  Fixed Typos and spelling mistakes [Tvrtko, Joonas]

Signed-off-by: default avatarRamalingam C <ramalingam.c@intel.com>
cc: Matthew Auld <matthew.auld@intel.com>
cc: Thomas Hellstrom <thomas.hellstrom@linux.intel.com>
cc: Daniel Vetter <daniel.vetter@ffwll.ch>
cc: Jon Bloomfield <jon.bloomfield@intel.com>
cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
cc: Kenneth Graunke <kenneth@whitecape.org>
cc: mesa-dev@lists.freedesktop.org
cc: Jordan Justen <jordan.l.justen@intel.com>
cc: Tony Ye <tony.ye@intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Acked-by: default avatarJordan Justen <jordan.l.justen@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220502141508.2327-1-ramalingam.c@intel.com
parent e180a7b2

include/uapi/drm/i915_drm.h

+16 −0
Original line number Diff line number Diff line
@@ -3443,6 +3443,22 @@ struct drm_i915_gem_create_ext { 
 * At which point we get the object handle in &drm_i915_gem_create_ext.handle,

 * along with the final object size in &drm_i915_gem_create_ext.size, which

 * should account for any rounding up, if required.

 *

 * Note that userspace has no means of knowing the current backing region

 * for objects where @num_regions is larger than one. The kernel will only

 * ensure that the priority order of the @regions array is honoured, either

 * when initially placing the object, or when moving memory around due to

 * memory pressure

 *

 * On Flat-CCS capable HW, compression is supported for the objects residing

 * in I915_MEMORY_CLASS_DEVICE. When such objects (compressed) have other

 * memory class in @regions and migrated (by i915, due to memory

 * constraints) to the non I915_MEMORY_CLASS_DEVICE region, then i915 needs to

 * decompress the content. But i915 doesn't have the required information to

 * decompress the userspace compressed objects.

 *

 * So i915 supports Flat-CCS, on the objects which can reside only on

 * I915_MEMORY_CLASS_DEVICE regions.

 */

struct drm_i915_gem_create_ext_memory_regions {

	/** @base: Extension link. See struct i915_user_extension. */