__u64 offset;
};
+/**
+ * struct drm_i915_gem_mmap_offset - Retrieve an offset so we can mmap this buffer object.
+ *
+ * This struct is passed as argument to the `DRM_IOCTL_I915_GEM_MMAP_OFFSET` ioctl,
+ * and is used to retrieve the fake offset to mmap an object specified by &handle.
+ *
+ * The legacy way of using `DRM_IOCTL_I915_GEM_MMAP` is removed on gen12+.
+ * `DRM_IOCTL_I915_GEM_MMAP_GTT` is an older supported alias to this struct, but will behave
+ * as setting the &extensions to 0, and &flags to `I915_MMAP_OFFSET_GTT`.
+ */
struct drm_i915_gem_mmap_offset {
- /** Handle for the object being mapped. */
+ /** @handle: Handle for the object being mapped. */
__u32 handle;
+ /** @pad: Must be zero */
__u32 pad;
/**
- * Fake offset to use for subsequent mmap call
+ * @offset: The fake offset to use for subsequent mmap call
*
* This is a fixed-size type for 32/64 compatibility.
*/
__u64 offset;
/**
- * Flags for extended behaviour.
+ * @flags: Flags for extended behaviour.
+ *
+ * It is mandatory that one of the `MMAP_OFFSET` types
+ * should be included:
+ *
+ * - `I915_MMAP_OFFSET_GTT`: Use mmap with the object bound to GTT. (Write-Combined)
+ * - `I915_MMAP_OFFSET_WC`: Use Write-Combined caching.
+ * - `I915_MMAP_OFFSET_WB`: Use Write-Back caching.
+ * - `I915_MMAP_OFFSET_FIXED`: Use object placement to determine caching.
*
- * It is mandatory that one of the MMAP_OFFSET types
- * (GTT, WC, WB, UC, etc) should be included.
+ * On devices with local memory `I915_MMAP_OFFSET_FIXED` is the only valid
+ * type. On devices without local memory, this caching mode is invalid.
+ *
+ * As caching mode when specifying `I915_MMAP_OFFSET_FIXED`, WC or WB will
+ * be used, depending on the object placement on creation. WB will be used
+ * when the object can only exist in system memory, WC otherwise.
*/
__u64 flags;
-#define I915_MMAP_OFFSET_GTT 0
-#define I915_MMAP_OFFSET_WC 1
-#define I915_MMAP_OFFSET_WB 2
-#define I915_MMAP_OFFSET_UC 3
- /*
- * Zero-terminated chain of extensions.
+#define I915_MMAP_OFFSET_GTT 0
+#define I915_MMAP_OFFSET_WC 1
+#define I915_MMAP_OFFSET_WB 2
+#define I915_MMAP_OFFSET_UC 3
+#define I915_MMAP_OFFSET_FIXED 4
+
+ /**
+ * @extensions: Zero-terminated chain of extensions.
*
* No current extensions defined; mbz.
*/
* - I915_GEM_DOMAIN_GTT: Mappable aperture domain
*
* All other domains are rejected.
+ *
+ * Note that for discrete, starting from DG1, this is no longer supported, and
+ * is instead rejected. On such platforms the CPU domain is effectively static,
+ * where we also only support a single &drm_i915_gem_mmap_offset cache mode,
+ * which can't be set explicitly and instead depends on the object placements,
+ * as per the below.
+ *
+ * Implicit caching rules, starting from DG1:
+ *
+ * - If any of the object placements (see &drm_i915_gem_create_ext_memory_regions)
+ * contain I915_MEMORY_CLASS_DEVICE then the object will be allocated and
+ * mapped as write-combined only.
+ *
+ * - Everything else is always allocated and mapped as write-back, with the
+ * guarantee that everything is also coherent with the GPU.
+ *
+ * Note that this is likely to change in the future again, where we might need
+ * more flexibility on future devices, so making this all explicit as part of a
+ * new &drm_i915_gem_create_ext extension is probable.
*/
struct drm_i915_gem_set_domain {
/** @handle: Handle for the object. */
* ppGTT support, or if the object is used for scanout). Note that this might
* require unbinding the object from the GTT first, if its current caching value
* doesn't match.
+ *
+ * Note that this all changes on discrete platforms, starting from DG1, the
+ * set/get caching is no longer supported, and is now rejected. Instead the CPU
+ * caching attributes(WB vs WC) will become an immutable creation time property
+ * for the object, along with the GTT caching level. For now we don't expose any
+ * new uAPI for this, instead on DG1 this is all implicit, although this largely
+ * shouldn't matter since DG1 is coherent by default(without any way of
+ * controlling it).
+ *
+ * Implicit caching rules, starting from DG1:
+ *
+ * - If any of the object placements (see &drm_i915_gem_create_ext_memory_regions)
+ * contain I915_MEMORY_CLASS_DEVICE then the object will be allocated and
+ * mapped as write-combined only.
+ *
+ * - Everything else is always allocated and mapped as write-back, with the
+ * guarantee that everything is also coherent with the GPU.
+ *
+ * Note that this is likely to change in the future again, where we might need
+ * more flexibility on future devices, so making this all explicit as part of a
+ * new &drm_i915_gem_create_ext extension is probable.
+ *
+ * Side note: Part of the reason for this is that changing the at-allocation-time CPU
+ * caching attributes for the pages might be required(and is expensive) if we
+ * need to then CPU map the pages later with different caching attributes. This
+ * inconsistent caching behaviour, while supported on x86, is not universally
+ * supported on other architectures. So for simplicity we opt for setting
+ * everything at creation time, whilst also making it immutable, on discrete
+ * platforms.
*/
struct drm_i915_gem_caching {
/**
__u32 pad;
};
+/**
+ * struct drm_i915_gem_userptr - Create GEM object from user allocated memory.
+ *
+ * Userptr objects have several restrictions on what ioctls can be used with the
+ * object handle.
+ */
struct drm_i915_gem_userptr {
+ /**
+ * @user_ptr: The pointer to the allocated memory.
+ *
+ * Needs to be aligned to PAGE_SIZE.
+ */
__u64 user_ptr;
+
+ /**
+ * @user_size:
+ *
+ * The size in bytes for the allocated memory. This will also become the
+ * object size.
+ *
+ * Needs to be aligned to PAGE_SIZE, and should be at least PAGE_SIZE,
+ * or larger.
+ */
__u64 user_size;
+
+ /**
+ * @flags:
+ *
+ * Supported flags:
+ *
+ * I915_USERPTR_READ_ONLY:
+ *
+ * Mark the object as readonly, this also means GPU access can only be
+ * readonly. This is only supported on HW which supports readonly access
+ * through the GTT. If the HW can't support readonly access, an error is
+ * returned.
+ *
+ * I915_USERPTR_UNSYNCHRONIZED:
+ *
+ * NOT USED. Setting this flag will result in an error.
+ */
__u32 flags;
#define I915_USERPTR_READ_ONLY 0x1
#define I915_USERPTR_UNSYNCHRONIZED 0x80000000
/**
- * Returned handle for the object.
+ * @handle: Returned handle for the object.
*
* Object handles are nonzero.
*/
projects / linux-2.6-microblaze.git / blobdiff