Document all of the DRM_CAP_* defines.
Signed-off-by: Simon Ser contact@emersion.fr Cc: Daniel Vetter daniel@ffwll.ch Cc: Pekka Paalanen ppaalanen@gmail.com --- 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. + */ #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. + */ #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. + */ #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. + */ #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. + */ #define DRM_CAP_TIMESTAMP_MONOTONIC 0x6 +/** + * DRM_CAP_ASYNC_PAGE_FLIP + * + * If set to 1, the driver supports &DRM_MODE_PAGE_FLIP_ASYNC. + */ #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. + */ #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 */
On Thu, 4 Mar 2021 23:10:57 +0100 Simon Ser contact@emersion.fr wrote:
Document all of the DRM_CAP_* defines.
Signed-off-by: Simon Ser contact@emersion.fr Cc: Daniel Vetter daniel@ffwll.ch Cc: Pekka Paalanen ppaalanen@gmail.com
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
On Friday, March 5th, 2021 at 9:28 AM, Pekka Paalanen ppaalanen@gmail.com wrote:
+/**
- DRM_CAP_DUMB_PREFERRED_DEPTH
- The preferred depth (in bits) for dumb buffers.
this is literally depth, not bits per pixel, right?
"Depth" is pretty ambiguous [1]. Maybe we should be more explicit here and say that it's the number of bits used to indicate the color of a single pixel? And maybe add a note that it's different from bits per pixel?
[1]: https://en.wikipedia.org/wiki/Color_depth
- */
#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?
Good call, will add.
- */
#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?
Will add something like:
PRIME buffers are exposed as dma-buf file descriptors. See Documentation/gpu/drm-mm.rst, section "PRIME Buffer Sharing".
- */
#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()?
Yes. Will add a note about it. Same for import.
- */
#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()?
Ack, better be explicit here.
- */
#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?
Yes (it's included in DRM_MODE_ATOMIC_FLAGS), but I heard that some drivers get it wrong.
- */
#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?
Both DRM_EVENT_VBLANK and DRM_EVENT_FLIP_COMPLETE use the struct drm_event_vblank, so yes. I'll mention these two events explicitly.
- */
#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. ;-)
Np :)
On Sat, 06 Mar 2021 10:56:49 +0000 Simon Ser contact@emersion.fr wrote:
On Friday, March 5th, 2021 at 9:28 AM, Pekka Paalanen ppaalanen@gmail.com wrote:
+/**
- DRM_CAP_DUMB_PREFERRED_DEPTH
- The preferred depth (in bits) for dumb buffers.
this is literally depth, not bits per pixel, right?
"Depth" is pretty ambiguous [1]. Maybe we should be more explicit here and say that it's the number of bits used to indicate the color of a single pixel? And maybe add a note that it's different from bits per pixel?
Yes, indeed. I was already assuming the meaning of "depth" in drmModeAddFB().
+/**
- 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?
Will add something like:
PRIME buffers are exposed as dma-buf file descriptors. See Documentation/gpu/drm-mm.rst, section "PRIME Buffer Sharing".
Sounds good.
- */
#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()?
Yes. Will add a note about it. Same for import.
Cool.
+/**
- 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?
Both DRM_EVENT_VBLANK and DRM_EVENT_FLIP_COMPLETE use the struct drm_event_vblank, so yes. I'll mention these two events explicitly.
They do? Seems like I have been spoiled by the libdrm API that uses drmEventContext with different callbacks for these things.
Thanks, pq
On Monday, March 8th, 2021 at 9:20 AM, Pekka Paalanen ppaalanen@gmail.com wrote:
+/**
- 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?
Both DRM_EVENT_VBLANK and DRM_EVENT_FLIP_COMPLETE use the struct drm_event_vblank, so yes. I'll mention these two events explicitly.
They do? Seems like I have been spoiled by the libdrm API that uses drmEventContext with different callbacks for these things.
Yeah, see drmHandleEvent [1] in libdrm.
[1]: https://gitlab.freedesktop.org/mesa/drm/-/blob/7d6a1759900ffde0a7aac2fa0cbd7...
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