dri-devel Archive on lore.kernel.org
 help / color / Atom feed
From: Simon Ser <contact@emersion.fr>
To: dri-devel@lists.freedesktop.org
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Subject: [PATCH v5 2/2] drm/doc: document the type plane property
Date: Fri, 15 Jan 2021 12:06:26 +0100
Message-ID: <20210115110626.12233-2-contact@emersion.fr> (raw)
In-Reply-To: <20210115110626.12233-1-contact@emersion.fr>

Add a new entry for "type" in the section for standard plane properties.

v3: improve paragraph about mixing legacy IOCTLs with explicit usage,
note that a driver may support cursors without cursor planes (Daniel)

v4: fixing rebase gone wrong

v5:
- Fix typo (Daniel)
- Mention CAP_ATOMIC instead of CAP_UNIVERSAL_PLANES when referring to
  atomic test-only commits (Daniel)
- Add newlines at end of sections (Daniel)

Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Pekka Paalanen <ppaalanen@gmail.com>
---
 drivers/gpu/drm/drm_plane.c | 58 ++++++++++++++++++++++++++++++++++---
 1 file changed, 54 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index bf6e525bb116..5affcc7f065b 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -50,10 +50,8 @@
  * &struct drm_plane (possibly as part of a larger structure) and registers it
  * with a call to drm_universal_plane_init().
  *
- * The type of a plane is exposed in the immutable "type" enumeration property,
- * which has one of the following values: "Overlay", "Primary", "Cursor" (see
- * enum drm_plane_type). A plane can be compatible with multiple CRTCs, see
- * &drm_plane.possible_crtcs.
+ * Each plane has a type, see enum drm_plane_type. A plane can be compatible
+ * with multiple CRTCs, see &drm_plane.possible_crtcs.
  *
  * Each CRTC must have a unique primary plane userspace can attach to enable
  * the CRTC. In other words, userspace must be able to attach a different
@@ -73,6 +71,58 @@
  *
  * DRM planes have a few standardized properties:
  *
+ * type:
+ *     Immutable property describing the type of the plane.
+ *
+ *     For user-space which has enabled the &DRM_CLIENT_CAP_ATOMIC capability,
+ *     the plane type is just a hint and is mostly superseded by atomic
+ *     test-only commits. The type hint can still be used to come up more
+ *     easily with a plane configuration accepted by the driver.
+ *
+ *     The value of this property can be one of the following:
+ *
+ *     "Primary":
+ *         To light up a CRTC, attaching a primary plane is the most likely to
+ *         work if it covers the whole CRTC and doesn't have scaling or
+ *         cropping set up.
+ *
+ *         Drivers may support more features for the primary plane, user-space
+ *         can find out with test-only atomic commits.
+ *
+ *         Primary planes are implicitly used by the kernel in the legacy
+ *         IOCTLs &DRM_IOCTL_MODE_SETCRTC and &DRM_IOCTL_MODE_PAGE_FLIP.
+ *         Therefore user-space must not mix explicit usage of any primary
+ *         plane (e.g. through an atomic commit) with these legacy IOCTLs.
+ *
+ *     "Cursor":
+ *         To enable this plane, using a framebuffer configured without scaling
+ *         or cropping and with the following properties is the most likely to
+ *         work:
+ *
+ *         - If the driver provides the capabilities &DRM_CAP_CURSOR_WIDTH and
+ *           &DRM_CAP_CURSOR_HEIGHT, create the framebuffer with this size.
+ *           Otherwise, create a framebuffer with the size 64x64.
+ *         - If the driver doesn't support modifiers, create a framebuffer with
+ *           a linear layout. Otherwise, use the IN_FORMATS plane property.
+ *
+ *         Drivers may support more features for the cursor plane, user-space
+ *         can find out with test-only atomic commits.
+ *
+ *         Cursor planes are implicitly used by the kernel in the legacy
+ *         IOCTLs &DRM_IOCTL_MODE_CURSOR and &DRM_IOCTL_MODE_CURSOR2.
+ *         Therefore user-space must not mix explicit usage of any cursor
+ *         plane (e.g. through an atomic commit) with these legacy IOCTLs.
+ *
+ *         Some drivers may support cursors even if no cursor plane is exposed.
+ *         In this case, the legacy cursor IOCTLs can be used to configure the
+ *         cursor.
+ *
+ *     "Overlay":
+ *         Neither primary nor cursor.
+ *
+ *         Overlay planes are the only planes exposed when the
+ *         &DRM_CLIENT_CAP_UNIVERSAL_PLANES capability is disabled.
+ *
  * IN_FORMATS:
  *     Blob property which contains the set of buffer format and modifier
  *     pairs supported by this plane. The blob is a struct
-- 
2.30.0

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-15 11:06 [PATCH v5 1/2] drm/doc: fix drm_plane_type docs Simon Ser
2021-01-15 11:06 ` Simon Ser [this message]
2021-01-18  8:52   ` [PATCH v5 2/2] drm/doc: document the type plane property Pekka Paalanen
2021-01-18  8:40 ` [PATCH v5 1/2] drm/doc: fix drm_plane_type docs Pekka Paalanen
2021-01-18  9:45   ` Daniel Vetter

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210115110626.12233-2-contact@emersion.fr \
    --to=contact@emersion.fr \
    --cc=daniel.vetter@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

dri-devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/dri-devel/0 dri-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dri-devel dri-devel/ https://lore.kernel.org/dri-devel \
		dri-devel@lists.freedesktop.org
	public-inbox-index dri-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.freedesktop.lists.dri-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git