Commit 6e29832f authored by Ramalingam C's avatar Ramalingam C
Browse files

drm/i915/gt: Document the eviction of the Flat-CCS objects 



Capture the eviction details for Flat-CCS capable, lmem objects.

v2:
  Fix the Flat-ccs capbility of lmem obj with smem residency
  possibility [Thomas]
v3:
  Fixed the suggestions [Matt]

Signed-off-by: default avatarRamalingam C <ramalingam.c@intel.com>
cc: Thomas Hellstrom <thomas.hellstrom@linux.intel.com>
cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220502142618.2704-4-ramalingam.c@intel.com
parent b8c9d486

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

+14 −9
Original line number Diff line number Diff line
@@ -485,16 +485,21 @@ static bool wa_1209644611_applies(int ver, u32 size) 
 * And CCS data can be copied in and out of CCS region through

 * XY_CTRL_SURF_COPY_BLT. CPU can't access the CCS data directly.

 *

 * When we exhaust the lmem, if the object's placements support smem, then we can

 * directly decompress the compressed lmem object into smem and start using it

 * from smem itself.

 * I915 supports Flat-CCS on lmem only objects. When an objects has smem in

 * its preference list, on memory pressure, i915 needs to migrate the lmem

 * content into smem. If the lmem object is Flat-CCS compressed by userspace,

 * then i915 needs to decompress it. But I915 lack the required information

 * for such decompression. Hence I915 supports Flat-CCS only on lmem only objects.

 *

 * But when we need to swapout the compressed lmem object into a smem region

 * though objects' placement doesn't support smem, then we copy the lmem content

 * as it is into smem region along with ccs data (using XY_CTRL_SURF_COPY_BLT).

 * When the object is referred, lmem content will be swaped in along with

 * restoration of the CCS data (using XY_CTRL_SURF_COPY_BLT) at corresponding

 * location.

 * When we exhaust the lmem, Flat-CCS capable objects' lmem backing memory can

 * be temporarily evicted to smem, along with the auxiliary CCS state, where

 * it can be potentially swapped-out at a later point, if required.

 * If userspace later touches the evicted pages, then we always move

 * the backing memory back to lmem, which includes restoring the saved CCS state,

 * and potentially performing any required swap-in.

 *

 * For the migration of the lmem objects with smem in placement list, such as

 * {lmem, smem}, objects are treated as non Flat-CCS capable objects.

 */



static inline u32 *i915_flush_dw(u32 *cmd, u32 flags)