Module Drm.Cap

Features offered by the Linux device driver to the application.

type 'a t
val get : 'a t -> Device.t -> ('a, Unix.error) Stdlib.result
val get_exn : 'a t -> Device.t -> 'a

Features

val dumb_buffer : bool t

The driver supports creating dumb buffers (via Buffer.Dumb.create).

val vblank_high_crtc : bool t

The kernel supports specifying a CRTC index in the high bits of drm_wait_vblank_request.type.

Starting kernel version 2.6.39, this capability is always set to true

val dumb_preferred_depth : int t

The preferred bit depth for dumb buffers.

The bit depth is the number of bits used to indicate the color of a single pixel excluding any padding. This is different from the number of bits per pixel. For instance, XRGB8888 has a bit depth of 24 but has 32 bits per pixel.

Note that this preference only applies to dumb buffers, it's irrelevant for other types of buffers.

val dumb_prefer_shadow : bool t

The driver prefers userspace to render to a shadow buffer instead of directly rendering to a dumb buffer. For best speed, userspace should do streaming ordered memory copies into the dumb buffer and never read from it.

Note that this preference only applies to dumb buffers, it's irrelevant for other types of buffers.

val prime : int t

Bitfield of supported PRIME sharing capabilities.

Starting from Linux version 6.6, both DRM_PRIME_CAP_IMPORT (1) and DRM_PRIME_CAP_EXPORT (2) are always advertised.

PRIME buffers are exposed as dma-buf file descriptors. See Dmabuf.

val timestamp_monotonic : bool t

If set to false, the kernel will report timestamps with CLOCK_REALTIME in struct drm_event_vblank. If set to true, the kernel will report timestamps with CLOCK_MONOTONIC. See clock_gettime(2) for the definition of these clocks.

Starting from kernel version 2.6.39, the default value for this capability is true. Starting kernel version 4.15, this capability is always set to true.

val async_page_flip : bool t

If set to true, the driver supports DRM_MODE_PAGE_FLIP_ASYNC for legacy page-flips.

val cursor_width : int t

The cursor_width and cursor_height capabilities return a valid width x height combination for the hardware cursor. The intention is that a hardware agnostic userspace can query a cursor plane size to use.

Note that the cross-driver contract is to merely return a valid size; drivers are free to attach another meaning on top, eg. i915 returns the maximum plane size.

val cursor_height : int t
val addfb2_modifiers : bool t

If set to true, the driver supports supplying modifiers in Kms.Fb.add.

val page_flip_target : bool t

If set to true, the driver supports the DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE and DRM_MODE_PAGE_FLIP_TARGET_RELATIVE flags in drm_mode_crtc_page_flip_target.flags for the DRM_IOCTL_MODE_PAGE_FLIP ioctl.

val crtc_in_vblank_event : bool t

If set to true, the kernel supports reporting the CRTC ID in drm_event_vblank.crtc_id for the DRM_EVENT_VBLANK and DRM_EVENT_FLIP_COMPLETE events.

Starting kernel version 4.12, this capability is always set to true.

val syncobj : bool t

If set to true, the driver supports sync objects.

val syncobj_timeline : bool t

If set to true, the driver supports timeline operations on sync objects.

val atomic_async_page_flip : bool t

If set to true, the driver supports DRM_MODE_PAGE_FLIP_ASYNC for atomic commits.