On Tue, Nov 12, 2024 at 04:28:28PM +0000, Matthew Auld wrote:
> Starting from LNL, CCS has moved over to flat CCS model where there is
> now dedicated memory reserved for storing compression state. On
> platforms like LNL this reserved memory lives inside graphics stolen
> memory, which is not treated like normal RAM and is therefore skipped by
> the core kernel when creating the hibernation image. Currently if
> something was compressed and we enter hibernation all the corresponding
> CCS state is lost on such HW, resulting in corrupted memory. To fix this
> evict user buffers from TT -> SYSTEM to ensure we take a snapshot of the
> raw CCS state when entering hibernation, where upon resuming we can
> restore the raw CCS state back when next validating the buffer. This has
> been confirmed to fix display corruption on LNL when coming back from
> hibernation.
>
> Fixes: cbdc52c11c9b ("drm/xe/xe2: Support flat ccs")
> Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/3409
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v6.8+
> ---
> drivers/gpu/drm/xe/xe_bo_evict.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_bo_evict.c b/drivers/gpu/drm/xe/xe_bo_evict.c
> index b01bc20eb90b..8fb2be061003 100644
> --- a/drivers/gpu/drm/xe/xe_bo_evict.c
> +++ b/drivers/gpu/drm/xe/xe_bo_evict.c
> @@ -35,10 +35,21 @@ int xe_bo_evict_all(struct xe_device *xe)
> int ret;
>
> /* User memory */
> - for (mem_type = XE_PL_VRAM0; mem_type <= XE_PL_VRAM1; ++mem_type) {
> + for (mem_type = XE_PL_TT; mem_type <= XE_PL_VRAM1; ++mem_type) {
> struct ttm_resource_manager *man =
> ttm_manager_type(bdev, mem_type);
>
> + /*
> + * On igpu platforms with flat CCS we need to ensure we save and restore any CCS
> + * state since this state lives inside graphics stolen memory which doesn't survive
> + * hibernation.
> + *
> + * This can be further improved by only evicting objects that we know have actually
> + * used a compression enabled PAT index.
yeap, but for now let's keep it simple...
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> + */
> + if (mem_type == XE_PL_TT && (IS_DGFX(xe) || !xe_device_has_flat_ccs(xe)))
> + continue;
> +
> if (man) {
> ret = ttm_resource_manager_evict_all(bdev, man);
> if (ret)
> --
> 2.47.0
>
