[PATCH RFC v2 1/2] drm/amdgpu: Add AMDGPU_BO_FLAG_CPU_ACCESS

[John Brooks]

For userspace BO allocations, replace AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED
with a new AMDGPU_BO_FLAG_CPU_ACCESS flag. This flag will be used to
indicate that a BO should currently be CPU accessible. Unlike the
CPU_ACCESS_REQUIRED flag, it is meant to be an ephemeral rather than a
permanent constraint. Currently, however, it is treated no differently.

v2: Put the new flag in amdgpu_drm.h, only clear CPU_ACCESS_REQUIRED if
    bo->tbo.type == ttm_bo_type_device (Christian König)

Signed-off-by: John Brooks <john at fastquake.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 9 ++++++++-
 include/uapi/drm/amdgpu_drm.h              | 2 ++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 8ee6965..a5e73f8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -128,7 +128,8 @@ static void amdgpu_ttm_placement_init(struct amdgpu_device *adev,
 		places[c].flags = TTM_PL_FLAG_WC | TTM_PL_FLAG_UNCACHED |
 			TTM_PL_FLAG_VRAM;
 
-		if (flags & AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED)
+		if (flags & (AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED |
+			     AMDGPU_BO_FLAG_CPU_ACCESS))
 			places[c].lpfn = visible_pfn;
 		else
 			places[c].flags |= TTM_PL_FLAG_TOPDOWN;
@@ -361,6 +362,12 @@ int amdgpu_bo_create_restricted(struct amdgpu_device *adev,
 	if (!kernel && bo->allowed_domains == AMDGPU_GEM_DOMAIN_VRAM)
 		bo->allowed_domains |= AMDGPU_GEM_DOMAIN_GTT;
 
+	if (flags & AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED) {
+		flags |= AMDGPU_BO_FLAG_CPU_ACCESS;
+		/* Treat CPU_ACCESS_REQUIRED only as a hint if given by UMD */
+		if (type == ttm_bo_type_device)
+			flags &= ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
+	}
 	bo->flags = flags;
 
 #ifdef CONFIG_X86_32
diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
index d9aa4a3..aeff910 100644
--- a/include/uapi/drm/amdgpu_drm.h
+++ b/include/uapi/drm/amdgpu_drm.h
@@ -87,6 +87,8 @@ extern "C" {
 #define AMDGPU_GEM_CREATE_SHADOW		(1 << 4)
 /* Flag that allocating the BO should use linear VRAM */
 #define AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS	(1 << 5)
+/* Flag that the BO is actively being used by the CPU. Internal use only */
+#define AMDGPU_BO_FLAG_CPU_ACCESS		(1 << 6)
 
 struct drm_amdgpu_gem_create_in  {
 	/** the requested memory size */
-- 
2.7.4