diff options
| -rw-r--r-- | drivers/gpu/drm/i915/gt/intel_migrate.c | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/drivers/gpu/drm/i915/gt/intel_migrate.c b/drivers/gpu/drm/i915/gt/intel_migrate.c index f80cea35b109..2c35324b5f68 100644 --- a/drivers/gpu/drm/i915/gt/intel_migrate.c +++ b/drivers/gpu/drm/i915/gt/intel_migrate.c @@ -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) |