[PATCH] drm/xe/lnl: Offload system clear page activity to GPU

[Nirmoy Das]

On LNL because of flat CCS, driver will create a migrate job to clear
CCS meta data. Extend that to also clear pages using GPU with new
ttm pool flag which allows offloading page clear activity to GPU.

Cc: Matthew Auld <matthew.a...@intel.com>
Cc: Michal Mrozek <michal.mro...@intel.com>
Cc: "Thomas Hellström" <thomas.hellst...@linux.intel.com>
Signed-off-by: Nirmoy Das <nirmoy....@intel.com>
---
 drivers/gpu/drm/xe/xe_bo.c           | 4 ++++
 drivers/gpu/drm/xe/xe_device.c       | 7 +++++++
 drivers/gpu/drm/xe/xe_device_types.h | 2 ++
 drivers/gpu/drm/xe/xe_migrate.c      | 5 +++--
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 65c696966e96..10ec02412dc4 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -387,6 +387,10 @@ static struct ttm_tt *xe_ttm_tt_create(struct 
ttm_buffer_object *ttm_bo,
                caching = ttm_uncached;
        }
 
+       /* Clear TTM_TT_FLAG_ZERO_ALLOC when GPU is set to clear pages */
+       if (xe->mem.gpu_page_clear)
+               page_flags &= ~TTM_TT_FLAG_ZERO_ALLOC;
+
        err = ttm_tt_init(&tt->ttm, &bo->ttm, page_flags, caching, extra_pages);
        if (err) {
                kfree(tt);
diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 0d57eea8f083..20548a5d3eff 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -636,6 +636,13 @@ int xe_device_probe(struct xe_device *xe)
        if (err)
                goto err_irq_shutdown;
 
+       /**
+        * On iGFX device with flat CCS we clear CCS metadata, let's extend that
+        * and use GPU to clear  pages as well.
+        */
+       if (xe_device_has_flat_ccs(xe) && !IS_DGFX(xe))
+               xe->mem.gpu_page_clear = true;
+
        err = xe_vram_probe(xe);
        if (err)
                goto err_irq_shutdown;
diff --git a/drivers/gpu/drm/xe/xe_device_types.h 
b/drivers/gpu/drm/xe/xe_device_types.h
index c37be471d11c..ece68c6f3668 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -325,6 +325,8 @@ struct xe_device {
                struct xe_mem_region vram;
                /** @mem.sys_mgr: system TTM manager */
                struct ttm_resource_manager sys_mgr;
+               /** @gpu_page_clear: clear pages offloaded to GPU */
+               bool gpu_page_clear;
        } mem;
 
        /** @sriov: device level virtualization data */
diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
index 05f933787860..90c5a2e35075 100644
--- a/drivers/gpu/drm/xe/xe_migrate.c
+++ b/drivers/gpu/drm/xe/xe_migrate.c
@@ -1003,6 +1003,7 @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
        struct xe_gt *gt = m->tile->primary_gt;
        struct xe_device *xe = gt_to_xe(gt);
        bool clear_system_ccs = (xe_bo_needs_ccs_pages(bo) && !IS_DGFX(xe)) ? 
true : false;
+       bool clear_on_create = xe->mem.gpu_page_clear;
        struct dma_fence *fence = NULL;
        u64 size = bo->size;
        struct xe_res_cursor src_it;
@@ -1032,7 +1033,7 @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
                batch_size = 2 +
                        pte_update_size(m, clear_vram, src, &src_it,
                                        &clear_L0, &clear_L0_ofs, &clear_L0_pt,
-                                       clear_system_ccs ? 0 : 
emit_clear_cmd_len(gt), 0,
+                                       !clear_on_create ? 0 : 
emit_clear_cmd_len(gt), 0,
                                        avail_pts);
 
                if (xe_device_has_flat_ccs(xe))
@@ -1060,7 +1061,7 @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
                bb->cs[bb->len++] = MI_BATCH_BUFFER_END;
                update_idx = bb->len;
 
-               if (!clear_system_ccs)
+               if (clear_on_create)
                        emit_clear(gt, bb, clear_L0_ofs, clear_L0, 
XE_PAGE_SIZE, clear_vram);
 
                if (xe_device_has_flat_ccs(xe)) {
-- 
2.42.0