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drm/amdgpu/ttm: Allocate/Free 4K MMIO_REMAP Singleton 

Add mmio_remap bookkeeping to amdgpu_device and introduce
amdgpu_ttm_mmio_remap_bo_init()/fini() to manage a kernel-owned,
one-page (4K) BO in AMDGPU_GEM_DOMAIN_MMIO_REMAP.

Bookkeeping:
  - adev->rmmio_remap.bo : kernel-owned singleton BO

The BO is allocated during TTM init when a remap bus address is available
(adev->rmmio_remap.bus_addr) and PAGE_SIZE <= AMDGPU_GPU_PAGE_SIZE (4K),
and freed during TTM fini.

v2:
 - Check mmio_remap bus address (adev->rmmio_remap.bus_addr) instead of
   rmmio_base. (Alex)
 - Skip quietly if PAGE_SIZE > AMDGPU_GPU_PAGE_SIZE or no bus address
   (no warn). (Alex)
 - Use `amdgpu_bo_create()` (not *_kernel) - Only with this The object
   is stored in adev->mmio_remap.bo and will later be exposed to
   userspace via a GEM handle. (Christian)

v3:
 - Remove obvious comment before amdgpu_ttm_mmio_remap_bo_fini() call.
   (Alex)

v4:
 - Squash bookkeeping into this patch (Christian)

Suggested-by: Christian König <christian.koenig@amd.com>
Suggested-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
pull/1354/merge
Srinivasan Shanmugam 2025-08-28 19:18:49 +05:30 committed by Alex Deucher
parent 9e46b8bb05
commit 2a7a794eb8
2 changed files with 60 additions and 0 deletions
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1
drivers/gpu/drm/amd/amdgpu/amdgpu.h
View File

@ -752,6 +752,7 @@ typedef void (*amdgpu_block_wreg_t)(struct amdgpu_device*, uint32_t, uint32_t, u
struct amdgpu_mmio_remap {
u32 reg_offset;
resource_size_t bus_addr;
struct amdgpu_bo *bo;
};
/* Define the HW IP blocks will be used in driver , add more if necessary */

59
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
View File

@ -1854,6 +1854,59 @@ static void amdgpu_ttm_pools_fini(struct amdgpu_device *adev)
adev->mman.ttm_pools = NULL;
}
/**
* amdgpu_ttm_mmio_remap_bo_init - Allocate the singleton 4K MMIO_REMAP BO
* @adev: amdgpu device
*
* Allocates a one-page (4K) GEM BO in AMDGPU_GEM_DOMAIN_MMIO_REMAP when the
* hardware exposes a remap base (adev->rmmio_remap.bus_addr) and the host
* PAGE_SIZE is <= AMDGPU_GPU_PAGE_SIZE (4K). The BO is created as a regular
* GEM object (amdgpu_bo_create).
*
* Return:
* * 0 on success or intentional skip (feature not present/unsupported)
* * negative errno on allocation failure
*/
static int amdgpu_ttm_mmio_remap_bo_init(struct amdgpu_device *adev)
{
struct amdgpu_bo_param bp;
int r;
/* Skip if HW doesn't expose remap, or if PAGE_SIZE > AMDGPU_GPU_PAGE_SIZE (4K). */
if (!adev->rmmio_remap.bus_addr || PAGE_SIZE > AMDGPU_GPU_PAGE_SIZE)
return 0;
memset(&bp, 0, sizeof(bp));
/* Create exactly one GEM BO in the MMIO_REMAP domain. */
bp.type = ttm_bo_type_device; /* userspace-mappable GEM */
bp.size = AMDGPU_GPU_PAGE_SIZE; /* 4K */
bp.byte_align = AMDGPU_GPU_PAGE_SIZE;
bp.domain = AMDGPU_GEM_DOMAIN_MMIO_REMAP;
bp.flags = 0;
bp.resv = NULL;
bp.bo_ptr_size = sizeof(struct amdgpu_bo);
r = amdgpu_bo_create(adev, &bp, &adev->rmmio_remap.bo);
if (r)
return r;
return 0;
}
/**
* amdgpu_ttm_mmio_remap_bo_fini - Free the singleton MMIO_REMAP BO
* @adev: amdgpu device
*
* Frees the kernel-owned MMIO_REMAP BO if it was allocated by
* amdgpu_ttm_mmio_remap_bo_init().
*/
static void amdgpu_ttm_mmio_remap_bo_fini(struct amdgpu_device *adev)
{
amdgpu_bo_unref(&adev->rmmio_remap.bo);
adev->rmmio_remap.bo = NULL;
}
/*
* amdgpu_ttm_init - Init the memory management (ttm) as well as various
* gtt/vram related fields.
@ -2028,6 +2081,11 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
return r;
}
/* Allocate the singleton MMIO_REMAP BO (4K) if supported */
r = amdgpu_ttm_mmio_remap_bo_init(adev);
if (r)
return r;
/* Initialize preemptible memory pool */
r = amdgpu_preempt_mgr_init(adev);
if (r) {
@ -2091,6 +2149,7 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev)
amdgpu_bo_free_kernel(&adev->mman.sdma_access_bo, NULL,
&adev->mman.sdma_access_ptr);
amdgpu_ttm_mmio_remap_bo_fini(adev);
amdgpu_ttm_fw_reserve_vram_fini(adev);
amdgpu_ttm_drv_reserve_vram_fini(adev);