sdk/fidl/fuchsia.sysmem/constraints.fidl

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
library fuchsia.sysmem;

using zx;

const MAX_COUNT_BUFFER_COLLECTION_CONSTRAINTS_IMAGE_FORMAT_CONSTRAINTS uint32 = 32;
const MAX_COUNT_BUFFER_MEMORY_CONSTRAINTS_HEAP_PERMITTED uint32 = 32;
const MAX_COUNT_IMAGE_FORMAT_CONSTRAINTS_COLOR_SPACES uint32 = 32;
const MAX_COUNT_BUFFER_COLLECTION_INFO_BUFFERS uint32 = 64;

// TODO(dustingreen): FIDL C generated code doesn't implement field defaults, so
// either move to FIDL C++ generated code (for this reason among several others;
// preferred), or make 0 values be aliases for the intended default value.  For
// now, the field defaults don't take effect and the field ends up having value
// 0 if not explicitly initialized, despite having a default value in the FIDL.

/// Constraints on BufferCollection parameters.  These constraints can be
/// specified per-participant.  The sysmem service implements aggregation of
/// constraints from multiple participants.
@for_deprecated_c_bindings
type BufferCollectionConstraints = struct {
    /// The usage is only meant as a hint to help sysmem choose a more optimal
    /// PixelFormat or similar when multiple compatible options exist.
    ///
    /// When aggregating BufferCollectionConstraints, these values bitwise-OR.
    ///
    /// At least one usage bit must be specified unless the whole
    /// BufferCollectionConstraints is logically null due to !has_constraints.
    usage BufferUsage;

    /// Per-participant number of buffers that the participant may concurrently
    /// hold for its exclusive use for a non-transient period of time (camp on).
    ///
    /// For example, a video decoder would specify (at least) the maximum number
    /// of reference frames + 1 frame currently being decoded into.
    ///
    /// A participant must not camp on more buffers than specified here (except
    /// very transiently) else processing may get stuck.
    ///
    /// When aggregating BufferCollectionConstraints, these values add.
    ///
    /// In testing scenarios, camping on more buffers than this for any
    /// significant duration may (ideally will) be flagged as a failure.  In
    /// testing scenarios, the participant may not be provided with more buffers
    /// than this concurrently.
    min_buffer_count_for_camping uint32;

    /// Per-participant minimum number of buffers that are needed for slack
    /// reasons, for better overlap of processing / better performance.
    ///
    /// When aggregating BufferCollectionConstraints, these values add.
    ///
    /// A participant should typically specify 0 or 1 here - typically 0 is
    /// appropriate if min_buffer_count_for_camping is already enough to keep
    /// the participant busy 100% of the time when the participant is slightly
    /// behind, while 1 can be appropriate if 1 more buffer than strictly needed
    /// for min-camping reasons gives enough slack to stay busy 100% of the time
    /// (when slightly behind, vs. lower % without the extra buffer).
    ///
    /// In testing scenarios, this field may be forced to 0, and all
    /// participants are expected to continue to work without getting stuck.  If
    /// a buffer is needed for forward progress reasons, that buffer should be
    /// accounted for in min_buffer_count_for_camping.
    min_buffer_count_for_dedicated_slack uint32;

    /// Similar to min_buffer_count_for_dedicated_slack, except when aggregating
    /// these values max (instead of add).  The value here is not shared with
    /// any participant's min_buffer_count_for_dedicated_slack.
    ///
    /// A participant can specify > 0 here if a participant would like to ensure
    /// there's some slack overall, but doesn't need that slack to be dedicated.
    ///
    /// The choice whether to use min_buffer_count_for_dedicated_slack or
    /// min_buffer_count_for_shared_slack (or both) will typically be about the
    /// degree to which the extra slack improves performance.
    ///
    /// In testing scenarios, this field may be forced to 0, and all
    /// participants are expected to continue to work without getting stuck.  If
    /// a buffer is needed for forward progress reasons, that buffer should be
    /// accounted for in min_buffer_count_for_camping.
    min_buffer_count_for_shared_slack uint32;

    /// A particularly-picky participant may unfortunately need to demand a
    /// tight range of buffer_count, or even a specific buffer_count.  This
    /// field should remain 0 unless a participant really must set this field to
    /// constrain the overall BufferCollectionInfo_2.buffer_count.  Any such
    /// participant should still fill out the min_buffer_count_for_* fields
    /// above.
    min_buffer_count uint32;
    /// 0 is treated as 0xFFFFFFFF.
    max_buffer_count uint32;

    /// Constraints on BufferCollectionSettings.buffer_settings.
    ///
    /// A participant that intends to specify image_format_constraints_count > 1
    /// will typically specify the minimum buffer size implicitly via
    /// image_format_constraints, and possibly specify only the max buffer size
    /// via buffer_memory_constraints.
    has_buffer_memory_constraints bool;
    buffer_memory_constraints BufferMemoryConstraints;

    /// Optional constraints on the image format parameters of an image stored
    /// in a buffer of the BufferCollection.  This includes pixel format and
    /// image layout.  These constraints are per-pixel-format, so more than one
    /// is permitted. Entries in the list must have unique pixel_formats.
    ///
    /// When aggregating, only pixel formats that are specified by all
    /// particpants with non-zero image_format_constraints_count (and non-Null)
    /// BufferCollectionConstraints) are retained.
    image_format_constraints_count uint32;
    image_format_constraints
            array<ImageFormatConstraints, MAX_COUNT_BUFFER_COLLECTION_CONSTRAINTS_IMAGE_FORMAT_CONSTRAINTS>;
};

@for_deprecated_c_bindings
type BufferCollectionConstraintsAuxBuffers = struct {
    /// If true, a secure heap may only be selected if all participants with
    /// BufferMemoryConstraints specify allow_clear_aux_buffers_for_secure.  If
    /// "need" is true, "allow" must also be true.
    ///
    /// If false, the participant can still work, potentially even with secure
    /// memory (depending on supported heaps), without clear aux buffers.
    need_clear_aux_buffers_for_secure bool;

    /// If true, the participant will use clear aux buffers, if they are
    /// allocated, as appropriate to the participant's role.  If the participant
    /// is a producer, then the participant producer will populate the clear aux
    /// buffers with the clear (not-encrypted, not-DRM-protected) bytes, and
    /// fill protected bytes with data that does not emulate start codes, such
    /// as 0xFF.
    ///
    /// If BufferCollectionConstraintsAuxBuffers is never sent by a
    /// participant, then "allow" is true iff the participant specifies usage
    /// which is read only.
    ///
    /// If unspecified by a participant with write usage, or false, the
    /// buffer collection won't be able to allocate if any participant specifies
    /// need_clear_aux_buffers_for_secure true.
    allow_clear_aux_buffers_for_secure bool;
};

@for_deprecated_c_bindings
type VmoBuffer = resource struct {
    /// The same VMO can be used by more than one CodecBuffer (only of the same
    /// buffer_lifetime_ordinal), but each vmo handle must be a separate handle.
    ///
    /// The vmo field can be 0 if this is a VmoBuffer in BufferCollectionInfo_2
    /// that's at or beyond BufferCollectionInfo_2.buffer_count.
    vmo zx.handle:<VMO, optional>;

    /// Offset within the VMO of the first usable byte.  Must be < the VMO's
    /// size in bytes, and leave sufficient room for
    /// BufferMemorySettings.size_bytes before the end of the VMO.
    vmo_usable_start uint64;
};

// TODO(fxbug.dev/32119): change struct to table
/// Information about a buffer collection and its buffers.
@for_deprecated_c_bindings
type BufferCollectionInfo_2 = resource struct {
    /// The total number of buffers.
    buffer_count uint32;

    /// These settings apply to all the buffers in the initial buffer allocation.
    settings SingleBufferSettings;

    /// VMO handles (and vmo_usable_start offset) for each buffer in the
    /// collection.
    ///
    /// If present, all the VMOs at or after index `buffer_count` are invalid
    /// (0) handles.
    ///
    /// All buffer VMO handles have identical size and access rights.  The size
    /// is in settings.buffer_settings.size_bytes.
    ///
    /// The VMO access rights are determined based on the usages which the
    /// client specified when allocating the buffer collection.  For example,
    /// a client which expressed a read-only usage will receive VMOs without
    /// write rights.  In addition, the rights can be attenuated by the
    /// parameter to BufferCollectionToken.Duplicate() calls.
    buffers array<VmoBuffer, MAX_COUNT_BUFFER_COLLECTION_INFO_BUFFERS>;
};

@for_deprecated_c_bindings
type SingleBufferInfo = resource struct {
    settings SingleBufferSettings;
    buffer VmoBuffer;
};

/// After the initial buffer allocation, it's allowed to close old buffers and
/// allocate new buffers.  When a new buffer is allocated its settings can
/// differ from the rest of the buffers in the collection, and the single
/// buffer's settings are delivered via OnSingleBufferAllocated() using this
/// struct:
@for_deprecated_c_bindings
type SingleBufferSettings = struct {
    buffer_settings BufferMemorySettings;

    /// Buffers holding data that is not uncompressed image data will not have
    /// this field set.  Buffers holding data that is uncompressed image data
    /// _may_ have this field set.
    ///
    /// At least for now, changing the PixelFormat requires re-allocating
    /// buffers.
    has_image_format_constraints bool;
    image_format_constraints ImageFormatConstraints;
};

/// Known heap types.
/// Device specific types should have bit 60 set. Top order bit is reserved
/// and should not be set.
type HeapType = strict enum : uint64 {
    SYSTEM_RAM = 0x0000000000000000;

    /// Heap used for amlogic protected memory.
    AMLOGIC_SECURE = 0x1000000000010000;

    /// Heap used for amlogic protected memory between decrypt and video decode.
    AMLOGIC_SECURE_VDEC = 0x1000000000010001;

    /// Heap used by goldfish vulkan for device-local memory.
    GOLDFISH_DEVICE_LOCAL = 0x1000000000020000;

    /// Heap used by goldfish vulkan for host-visible memory.
    GOLDFISH_HOST_VISIBLE = 0x1000000000020001;

    /// Heap used for display framebuffer. This is used by display drivers
    /// limited to a single framebuffer located at a specific physical address.
    /// The framebuffer heap makes it possible to create buffer collections
    /// for the framebuffer and enables sysmem support in these drivers.
    FRAMEBUFFER = 0x1000000000030001;
};

@for_deprecated_c_bindings
type BufferMemoryConstraints = struct {
    @allow_deprecated_struct_defaults
    min_size_bytes uint32 = 0;
    /// 0 is treated as 0xFFFFFFFF.
    @allow_deprecated_struct_defaults
    max_size_bytes uint32 = 0xFFFFFFFF;

    @allow_deprecated_struct_defaults
    physically_contiguous_required bool = false;

    /// If true, at least one participant requires secure memory.
    ///
    /// When aggregating BufferCollectionConstraints, these values boolean-OR.
    @allow_deprecated_struct_defaults
    secure_required bool = false;

    /// By default, participants must ensure the CPU can read or write data to
    /// the buffer without cache operations. If they support using the RAM
    /// domain, data must be available in RAM (with CPU cache state such that
    /// the RAM data won't get corrupted by a dirty CPU cache line writing
    /// incorrect data to RAM), and a consumer reading using the CPU must
    /// invalidate CPU cache before reading (the producer doesn't guarantee
    /// zero stale "clean" cache lines)
    @allow_deprecated_struct_defaults
    ram_domain_supported bool = false;
    @allow_deprecated_struct_defaults
    cpu_domain_supported bool = true;
    @allow_deprecated_struct_defaults
    inaccessible_domain_supported bool = false;

    /// Optional heap constraints. Participants that don't care which heap
    /// memory is allocated on should leave this field 0.
    heap_permitted_count uint32;
    heap_permitted array<HeapType, MAX_COUNT_BUFFER_MEMORY_CONSTRAINTS_HEAP_PERMITTED>;
};

/// Inaccessible is only for cases where there is no CPU-based access to the
/// buffers.  A secure_required buffer can still have CoherencyDomain Cpu or
/// Ram even if the secure_required buffer can only be accessed by the CPU when
/// the CPU is running in secure mode (or similar).  In contrast, device-local
/// memory that isn't reachable from the CPU is CoherencyDomain Inaccessible,
/// even if it's possible to cause a device (physical or virtual) to copy the
/// data from the Inaccessible buffers to buffers that are visible to the CPU.
type CoherencyDomain = strict enum {
    CPU = 0;
    RAM = 1;
    INACCESSIBLE = 2;
};

@for_deprecated_c_bindings
type BufferMemorySettings = struct {
    size_bytes uint32;
    is_physically_contiguous bool;
    is_secure bool;
    coherency_domain CoherencyDomain;
    /// The specific heap from which buffers are allocated.
    /// See above in this file for heap identifier values.
    heap HeapType;
};

// TODO(fxbug.dev/32119): change struct to table
/// Describes constraints on layout of image data in buffers.
@for_deprecated_c_bindings
type ImageFormatConstraints = struct {
    /// The PixelFormat for which the following constraints apply.  A
    /// participant may have more than one PixelFormat that's supported, in
    /// which case that participant can use a list of ImageFormatConstraints
    /// with an entry per PixelFormat.  It's not uncommon for the other fields
    /// of ImageFormatConstraints to vary by PixelFormat - for example for a
    /// linear format to support smaller max size than a tiled format.
    pixel_format PixelFormat;

    /// Empty is an error.  Redundant entries are an error.  Arbitrary ordering
    /// is not an error.
    color_spaces_count uint32;
    color_space array<ColorSpace, MAX_COUNT_IMAGE_FORMAT_CONSTRAINTS_COLOR_SPACES>;

    /// Minimum permitted width in pixels.
    ///
    /// For example a video decoder participant may set this field to the
    /// minimum coded_width that might potentially be specified by a stream.  In
    /// contrast, required_min_coded_width would be set to the current
    /// coded_width specified by the stream.  While min_coded_width aggregates
    /// by taking the max, required_min_coded_width aggregates by taking the
    /// min.
    ///
    /// See also required_min_coded_width.
    min_coded_width uint32;
    /// Maximum width in pixels.  For example Scenic may set this field
    /// (directly or via sub-participants) to the maximum width that can be
    /// composited.
    /// 0 is treated as 0xFFFFFFFF.
    max_coded_width uint32;

    /// Minimum height in pixels.  For example a video decoder participant may
    /// set this field to the coded_height specified by a stream.
    min_coded_height uint32;
    /// Maximum height in pixels.  For example Scenic may set this field
    /// (directly or via sub-participants) to the maximum height that can be
    /// composited.
    /// 0 is treated as 0xFFFFFFFF.
    max_coded_height uint32;

    /// Must be >= the value implied by min_coded_width for plane 0.
    min_bytes_per_row uint32;
    /// Must be >= the value implied by max_coded_width for plane 0.
    /// 0 is treated as 0xFFFFFFFF.
    max_bytes_per_row uint32;

    /// The max image area in pixels is limited indirectly via
    /// BufferSettings.size_bytes, and can also be enforced directly via this
    /// field.
    /// 0 is treated as 0xFFFFFFFF.
    @allow_deprecated_struct_defaults
    max_coded_width_times_coded_height uint32 = 0xFFFFFFFF;

    /// Number of layers within a multi-layered image.
    /// 0 is treated as 1.
    @allow_deprecated_struct_defaults
    layers uint32 = 1;

    /// coded_width % width_divisor must be 0.
    /// 0 is treated as 1.
    @allow_deprecated_struct_defaults
    coded_width_divisor uint32 = 1;

    /// coded_height % height_divisor must be 0.
    /// 0 is treated as 1.
    @allow_deprecated_struct_defaults
    coded_height_divisor uint32 = 1;

    /// bytes_per_row % bytes_per_row_divisor must be 0.
    /// 0 is treated as 1.
    @allow_deprecated_struct_defaults
    bytes_per_row_divisor uint32 = 1;

    /// vmo_usable_start % start_offset_divisor must be 0.
    /// 0 is treated as 1.
    @allow_deprecated_struct_defaults
    start_offset_divisor uint32 = 1;

    /// display_width % display_width_divisor must be 0.
    /// 0 is treated as 1.
    @allow_deprecated_struct_defaults
    display_width_divisor uint32 = 1;

    /// display_height % display_height_divisor must be 0.
    /// 0 is treated as 1.
    @allow_deprecated_struct_defaults
    display_height_divisor uint32 = 1;

    /// required_ dimension bounds.
    ///
    /// In contrast to the corresponding fields without "required_" at the
    /// start, these fields (when set to non-zero values) express a requirement
    /// that the resulting aggregated non-required_ fields specify a space that
    /// fully contain the space expressed by each participant's required_
    /// fields.
    ///
    /// For example, a producer video decoder is perfectly happy for the
    /// consumer to be willing to accept anything, and the video decoder doesn't
    /// really want to constrain the potential space of dimensions that might be
    /// seen in a stream and may be acceptable to the consumer, but the video
    /// decoder needs to ensure that the resulting dimension ranges contain
    /// at least the current dimensions decoded from the stream.
    ///
    /// Similarly, an initiator with a particular dynamic-dimension scenario in
    /// mind may wish to require up front that participants agree to handle at
    /// least the range of dimensions expected by the initiator in that
    /// scenario (else fail earlier rather than later, maybe trying again with
    /// smaller required_ space).
    ///
    /// It's much more common for a producer or initiator to set these fields
    /// than for a consumer to set these fields.
    ///
    /// While the non-required_ fields aggregate by taking the intersection, the
    /// required_ fields aggregate by taking the union.
    ///
    /// If set, the required_max_coded_width and required_max_coded_height will
    /// cause the allocated buffers to be large enough to hold an image that is
    /// required_max_coded_width * required_max_coded_height.
    ///
    /// TODO(dustingreen): Make it easier to allocate buffers of minimal size
    /// that can (optionally) also handle 90 degree rotated version of the max
    /// dimensions / alternate required bounds for another main aspect ratio.
    /// 0 is treated as 0xFFFFFFFF.
    required_min_coded_width uint32;
    required_max_coded_width uint32;
    /// 0 is treated as 0xFFFFFFFF.
    required_min_coded_height uint32;
    required_max_coded_height uint32;
    /// 0 is treated as 0xFFFFFFFF.
    required_min_bytes_per_row uint32;
    required_max_bytes_per_row uint32;
};

// TODO(fxbug.dev/32119): change struct to table
/// Describes how an image is represented.
@for_deprecated_c_bindings
type ImageFormat_2 = struct {
    /// Pixel format.
    pixel_format PixelFormat;

    /// Row width in pixels that exist in the buffer.  Must be >= display_width.
    /// Can be < the width implied by stride_bytes.
    coded_width uint32;

    /// Number of rows.  Must be >= display_height.
    coded_height uint32;

    // Stride in bytes of plane 0.  Planes beyond plane 0 (if any, depending on
    // pixel_format) have a known fixed relationship with plane 0's stride.
    bytes_per_row uint32;

    /// Row width in pixels that are to be displayed.  This can be <=
    /// coded_width.  Any cropping occurs on the right of the image (not left).
    display_width uint32;

    /// Number of rows to be displayed.  This can be <= coded_height, with any
    /// cropping on the bottom (not top).
    display_height uint32;

    /// Number of layers within a multi-layered image.
    @allow_deprecated_struct_defaults
    layers uint32 = 1;

    /// Color space.
    color_space ColorSpace;

    /// The pixel_aspect_ratio_width : pixel_aspect_ratio_height is the
    /// pixel aspect ratio (AKA sample aspect ratio aka SAR) for the luma
    /// (AKA Y) samples. A pixel_aspect_ratio of 1:1 mean square pixels. A
    /// pixel_aspect_ratio of 2:1 would mean pixels that are displayed twice
    /// as wide as they are tall. Codec implementation should ensure these
    /// two values are relatively prime by reducing the fraction (dividing
    /// both by GCF) if necessary.
    ///
    /// When has_pixel_aspect_ratio == false, the pixel_aspect_ratio is unknown.
    /// A default of 1:1 can be appropriate in some cases, but as always, a
    /// consumer may determine the actual pixel_aspect_ratio by OOB means.
    @allow_deprecated_struct_defaults
    has_pixel_aspect_ratio bool = false;
    @allow_deprecated_struct_defaults
    pixel_aspect_ratio_width uint32 = 1;
    @allow_deprecated_struct_defaults
    pixel_aspect_ratio_height uint32 = 1;
};