On Thu, 4 Mar 2021 23:10:57 +0100
Simon Ser <contact@xxxxxxxxxxx> wrote:
> Document all of the DRM_CAP_* defines.
>
> Signed-off-by: Simon Ser <contact@xxxxxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: Pekka Paalanen <ppaalanen@xxxxxxxxx>
> ---
> include/uapi/drm/drm.h | 100 +++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 96 insertions(+), 4 deletions(-)
>
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 0827037c5484..4ef07f505725 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -625,30 +625,122 @@ struct drm_gem_open {
> __u64 size;
> };
>
> +/**
> + * DRM_CAP_DUMB_BUFFER
> + *
> + * If set to 1, the driver supports creating dumb buffers via the
> + * &DRM_IOCTL_MODE_CREATE_DUMB ioctl.
> + */
> #define DRM_CAP_DUMB_BUFFER 0x1
> +/**
> + * DRM_CAP_VBLANK_HIGH_CRTC
> + *
> + * If set to 1, the kernel supports specifying a CRTC index in the high bits of
> + * &drm_wait_vblank_request.type.
> + */
> #define DRM_CAP_VBLANK_HIGH_CRTC 0x2
> +/**
> + * DRM_CAP_DUMB_PREFERRED_DEPTH
> + *
> + * The preferred depth (in bits) for dumb buffers.
Hi,
this is literally depth, not bits per pixel, right?
> + */
> #define DRM_CAP_DUMB_PREFERRED_DEPTH 0x3
> +/**
> + * DRM_CAP_DUMB_PREFER_SHADOW
> + *
> + * If set to 1, the driver prefers userspace to render to a shadow buffer
> + * instead of directly rendering to a dumb buffer.
Maybe add something like:
For best speed, userspace should do streaming ordered memory copies
into the dumb buffer and never read from it.
Isn't that correct?
> + */
> #define DRM_CAP_DUMB_PREFER_SHADOW 0x4
> +/**
> + * DRM_CAP_PRIME
> + *
> + * Bitfield of supported PRIME sharing capabilities. See &DRM_PRIME_CAP_IMPORT
> + * and &DRM_PRIME_CAP_EXPORT.
> + */
> #define DRM_CAP_PRIME 0x5
> +/**
> + * DRM_PRIME_CAP_IMPORT
> + *
> + * If this bit is set in &DRM_CAP_PRIME, the driver supports importing PRIME
> + * buffers.
What are PRIME buffers?
> + */
> #define DRM_PRIME_CAP_IMPORT 0x1
> +/**
> + * DRM_PRIME_CAP_EXPORT
> + *
> + * If this bit is set in &DRM_CAP_PRIME, the driver supports exporting PRIME
> + * buffers.
What's the export API? HandleToFD()?
> + */
> #define DRM_PRIME_CAP_EXPORT 0x2
> +/**
> + * DRM_CAP_TIMESTAMP_MONOTONIC
> + *
> + * If set to 0, the kernel will report timestamps with the realtime clock in
> + * struct drm_event_vblank. If set to 1, the kernel will report timestamps with
> + * the monotonic clock.
I think it would be more explicit to say CLOCK_REALTIME and
CLOCK_MONOTONIC, because there are things like CLOCK_MONOTONIC_RAW
which is different. Mention clock_gettime()?
> + */
> #define DRM_CAP_TIMESTAMP_MONOTONIC 0x6
> +/**
> + * DRM_CAP_ASYNC_PAGE_FLIP
> + *
> + * If set to 1, the driver supports &DRM_MODE_PAGE_FLIP_ASYNC.
Does this apply equally to both legacy and atomic KMS API?
> + */
> #define DRM_CAP_ASYNC_PAGE_FLIP 0x7
> -/*
> - * The CURSOR_WIDTH and CURSOR_HEIGHT capabilities return a valid widthxheight
> - * combination for the hardware cursor. The intention is that a hardware
> - * agnostic userspace can query a cursor plane size to use.
> +/**
> + * DRM_CAP_CURSOR_WIDTH
> + *
> + * 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.
> */
> #define DRM_CAP_CURSOR_WIDTH 0x8
> +/**
> + * DRM_CAP_CURSOR_HEIGHT
> + *
> + * See &DRM_CAP_CURSOR_WIDTH.
> + */
> #define DRM_CAP_CURSOR_HEIGHT 0x9
> +/**
> + * DRM_CAP_ADDFB2_MODIFIERS
> + *
> + * If set to 1, the driver supports supplying modifiers in the
> + * &DRM_IOCTL_MODE_ADDFB2 ioctl.
> + */
> #define DRM_CAP_ADDFB2_MODIFIERS 0x10
> +/**
> + * DRM_CAP_PAGE_FLIP_TARGET
> + *
> + * If set to 1, 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.
> + */
> #define DRM_CAP_PAGE_FLIP_TARGET 0x11
> +/**
> + * DRM_CAP_CRTC_IN_VBLANK_EVENT
> + *
> + * If set to 1, the kernel supports reporting the CRTC ID in
> + * &drm_event_vblank.crtc_id.
Does this not apply also to the pageflip / atomic completion event?
> + */
> #define DRM_CAP_CRTC_IN_VBLANK_EVENT 0x12
> +/**
> + * DRM_CAP_SYNCOBJ
> + *
> + * If set to 1, the driver supports sync objects. See
> + * Documentation/gpu/drm-mm.rst, section "DRM Sync Objects".
> + */
> #define DRM_CAP_SYNCOBJ 0x13
> +/**
> + * DRM_CAP_SYNCOBJ_TIMELINE
> + *
> + * If set to 1, the driver supports timeline operations on sync objects. See
> + * Documentation/gpu/drm-mm.rst, section "DRM Sync Objects".
> + */
> #define DRM_CAP_SYNCOBJ_TIMELINE 0x14
>
> /* DRM_IOCTL_GET_CAP ioctl argument type */
I'm so happy seeing this doc appear! :-)
Sorry for trolling you into it. ;-)
Thanks,
pq
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