[Intel-gfx] [PATCH 16/20] drm/i915/create: apply ALLOC_TOPDOWN by default

Matthew Auld
2022-01-26T15:23:12Z

Starting from DG2+, when dealing with LMEM, we assume that by default
all userspace allocations should be placed in the non-mappable portion
of LMEM. Note that dumb buffers are not included here, since these are
not "GPU accelerated" and likely need CPU access.

In a later patch userspace will be able to provide a hint if CPU access
to the buffer is needed.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
---
drivers/gpu/drm/i915/gem/i915_gem_create.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_create.c b/drivers/gpu/drm/i915/gem/i915_gem_create.c
index 9402d4bf4ffc..e7456443f163 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_create.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_create.c
@@ -424,6 +424,15 @@ i915_gem_create_ext_ioctl(struct drm_device *dev, void *data,
ext_data.n_placements = 1;
}

+ /*
+ * TODO: add a userspace hint to force CPU_ACCESS for the object, which
+ * can override this.
+ */
+ if (!IS_DG1(i915) && (ext_data.n_placements > 1 ||
+ ext_data.placements[0]->type !=
+ INTEL_MEMORY_SYSTEM))
+ ext_data.flags |= I915_BO_ALLOC_TOPDOWN;
+
obj = __i915_gem_object_create_user_ext(i915, args->size,
ext_data.placements,
ext_data.n_placements,
--
2.34.1