[RFC PATCH v2 2/8] drm/amdgpu/ttm: Add New AMDGPU_PL_MMIO_REMAP Placement

Srinivasan Shanmugam srinivasan.shanmugam at amd.com
Sat Aug 23 07:20:10 UTC 2025


Introduce a kernel-internal TTM placement type AMDGPU_PL_MMIO_REMAP
for the HDP flush MMIO remap page

Plumbing added:
- amdgpu_res_cursor.{first,next}: treat MMIO_REMAP like DOORBELL
- amdgpu_ttm_io_mem_reserve(): return BAR bus address + offset
  for MMIO_REMAP, mark as uncached I/O
- amdgpu_ttm_io_mem_pfn(): PFN from register BAR
- amdgpu_res_cpu_visible(): visible to CPU
- amdgpu_evict_flags()/amdgpu_bo_move(): non-migratable
- amdgpu_ttm_tt_pde_flags(): map as SYSTEM
- amdgpu_bo_mem_stats_placement(): report AMDGPU_PL_MMIO_REMAP
- amdgpu_fdinfo: print “mmioremap” bucket label

Notes:
- This patch bumps __AMDGPU_PL_NUM and (for now) TTM_NUM_MEM_TYPES to
  avoid compile-time guards.

Cc: Christian König <christian.koenig at amd.com>
Cc: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 3 ++-
 include/drm/ttm/ttm_resource.h          | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
index 2309df3f68a9..bb17987f0447 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
@@ -34,7 +34,8 @@
 #define AMDGPU_PL_OA		(TTM_PL_PRIV + 2)
 #define AMDGPU_PL_PREEMPT	(TTM_PL_PRIV + 3)
 #define AMDGPU_PL_DOORBELL	(TTM_PL_PRIV + 4)
-#define __AMDGPU_PL_NUM	(TTM_PL_PRIV + 5)
+#define AMDGPU_PL_MMIO_REMAP	(TTM_PL_PRIV + 5)
+#define __AMDGPU_PL_NUM	(TTM_PL_PRIV + 6)
 
 #define AMDGPU_GTT_MAX_TRANSFER_SIZE	512
 #define AMDGPU_GTT_NUM_TRANSFER_WINDOWS	2
diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h
index e52bba15012f..f49daa504c36 100644
--- a/include/drm/ttm/ttm_resource.h
+++ b/include/drm/ttm/ttm_resource.h
@@ -36,7 +36,7 @@
 #include <drm/ttm/ttm_kmap_iter.h>
 
 #define TTM_MAX_BO_PRIORITY	4U
-#define TTM_NUM_MEM_TYPES 8
+#define TTM_NUM_MEM_TYPES 9
 
 struct dmem_cgroup_device;
 struct ttm_device;
-- 
2.34.1



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