[PATCH wayland-protocols v3] unstable/drm-lease: DRM lease protocol support
Marius Vlad
marius-cristian.vlad at nxp.com
Mon Aug 20 20:00:48 UTC 2018
Simple protocol extension to manage DRM lease. Based on the work by Keith
Packard in [1], respectively [2].
[1] https://cgit.freedesktop.org/mesa/drm/commit/?id=c4171535389d72e9135c9615cecd07b346fd6d7e
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v4.15-rc9&id=62884cd386b876638720ef88374b31a84ca7ee5f
Signed-off-by: Marius Vlad <marius-cristian.vlad at nxp.com>
Changes since v2:
- advertise connector names when creating a lease request object (Pekka Paalanen)
- when revoking the lease use the lease object instead of lessee id (Pekka Paalanen)
- various grammar/spelling fixes (Pekka Paalanen)
Changes since v1:
- added manager: advertise lease capability and manage the lease (Daniel Stone)
- add request(s) for adding connector/crtc/plane to behave more like dmabuf (Daniel Stone)
---
Some caveats while at it. This is just in RFC form adapted from the comments
I've mostly got from Pekka Paalanen. It most certainly doesn't address all the issues
brought up: like multi-node card environments/system, doing a TEST_ONLY
commit before giving out a lease, or takes hot-plugging into consideration.
As I was side-tracked to other things and
being on hiatus for a while, I wanted first to get some impressions first if
indeed this is the right approach and do some incremental updates afterwards.
The are some issues which I'd like to point out from the beginning, which
require some further comments. In no particular order:
I've found that I can't pass a wl_array as a way to advertise various
information to the client. (wl_array works fine with integers not with
allocated data). It would probably be better to advertise also
monitor name, other EDID info or available modes, but at the moment I only
join-split a delimiter between connector names and send it out as a string.
While it is ugly I'm not aware of a way to send this information back to the
client in the form of a list.
The client is aware before hand of this delimiter and has the number of entries:
can easily choose or pick one of the connectors. It could be that there are
some other ways this can be achieved, I welcome any kind of feedback here.
Secondly, when doing a modeset, the client requires a valid mode
(drmModeModeInfo). I'm currently unsure how to pass this back to the client.
The obvious type="object" interface="drmModeModeInfo" fails to link and instead
I rely on the fact that a) the client can retrieve IDs from the lease using
lease API (drmModeGetLease()) which gives a connector id --
or alternately can also use a wl_array to pass that,
and b) the client can use the leased fd to iterate over connectors.
Matching those two would allow to get a valid
drmModeModeInfo object to pass it when modesetting (for more info
see the client implementation provided at the end).
Question is, is this an acceptable way of doing it? Do note that this
can only be "used" after the lease has been created.
A server/client implementation to match this protocol
can be found at https://gitlab.freedesktop.org/marius.vlad0/weston/commits/new-drm-lease
Makefile.am | 1 +
unstable/drm-lease/README | 4 +
unstable/drm-lease/drm-lease-unstable-v1.xml | 173 +++++++++++++++++++++++++++
3 files changed, 178 insertions(+)
create mode 100644 unstable/drm-lease/README
create mode 100644 unstable/drm-lease/drm-lease-unstable-v1.xml
diff --git a/Makefile.am b/Makefile.am
index 6394e26..5d13dca 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -4,6 +4,7 @@ unstable_protocols = \
unstable/pointer-gestures/pointer-gestures-unstable-v1.xml \
unstable/fullscreen-shell/fullscreen-shell-unstable-v1.xml \
unstable/linux-dmabuf/linux-dmabuf-unstable-v1.xml \
+ unstable/drm-lease/drm-lease-unstable-v1.xml \
unstable/text-input/text-input-unstable-v1.xml \
unstable/text-input/text-input-unstable-v3.xml \
unstable/input-method/input-method-unstable-v1.xml \
diff --git a/unstable/drm-lease/README b/unstable/drm-lease/README
new file mode 100644
index 0000000..a25600c
--- /dev/null
+++ b/unstable/drm-lease/README
@@ -0,0 +1,4 @@
+Linux DRM lease
+
+Maintainers:
+Marius Vlad <marius-cristian.vlad at nxp.com>
diff --git a/unstable/drm-lease/drm-lease-unstable-v1.xml b/unstable/drm-lease/drm-lease-unstable-v1.xml
new file mode 100644
index 0000000..6cb3c0a
--- /dev/null
+++ b/unstable/drm-lease/drm-lease-unstable-v1.xml
@@ -0,0 +1,173 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="drm_lease_unstable_v1">
+
+<copyright>
+ Copyright 2018 NXP
+
+ Permission is hereby granted, free of charge, to any person obtaining a
+ copy of this software and associated documentation files (the "Software"),
+ to deal in the Software without restriction, including without limitation
+ the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ and/or sell copies of the Software, and to permit persons to whom the
+ Software is furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice (including the next
+ paragraph) shall be included in all copies or substantial portions of the
+ Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ DEALINGS IN THE SOFTWARE.
+</copyright>
+
+ <interface name="zwp_kms_lease_manager_v1" version="1">
+ <description summary="lease manager">
+ This interface makes use of DRM lease written by Keith Packard.
+
+ A DRM master can create another DRM master and ``lease'' resources it has
+ control over to the new DRM master. Once leased, resources can not be
+ controlled by the owner unless the owner cancels the lease, or the new
+ DRM master is closed.
+
+ A lease is a contract between the Lessor (DRM master which has leased out
+ resources to one or more other DRM masters) and a Lessee
+ (DRM master which controls resources leased from another DRM master). This
+ contract specifies which resources may be controlled by the Lessee.
+
+ The Lessee can issue modesetting/page-flipping atomic operations etc.,
+ just like a Lessor using the leased file-descriptor passed by the Lessor.
+
+ Besides the leased file-descriptor, an integer is used to uniquely
+ identify a Lessee within the tree of DRM masters descending from a single
+ Owner. Once the Lessee has finished with the resources it had used, the
+ Lessee ID can be used to revoke that lease.
+
+ Warning! The protocol described in this file is experimental and
+ backward incompatible changes may be made. Backward compatible changes
+ may be added together with the corresponding interface version bump.
+ Backward incompatible changes are done by bumping the version number in
+ the protocol and interface names and resetting the interface version.
+ Once the protocol is to be declared stable, the 'z' prefix and the
+ version number in the protocol and interface names are removed and the
+ interface version number is reset.
+ </description>
+
+ <request name="destroy" type="destructor">
+ <description summary="destroys the manager">
+ This has no effect on any remaining objects created through this
+ interface.
+ </description>
+ </request>
+
+ <request name="create_lease_req">
+ <description summary="create a temporary object for managing the lease">
+ Create an object for temporarily storing all the KMS resources to be leased.
+ </description>
+ <arg name="params_id" type="new_id" interface="zwp_kms_lease_request_v1"
+ summary="the new temporary"/>
+ </request>
+
+ <event name="connectors">
+ <description summary="advertise which connectors can be used to request creation for a lease">
+ This event advertises leasable connectors. When multiple connectors are
+ advertised, the client should properly parse and choose one of connectors
+ A client trying to create a lease using zwp_kms_lease_request_v1::create
+ request would use this connector name.
+ </description>
+ <arg name="connectors" type="string" summary="list of connector entries, split by '|' char"/>
+ <arg name="connectors_entries" type="uint" summary="number of connectors found in connectors string"/>
+ </event>
+
+ </interface>
+
+ <interface name="zwp_kms_lease_v1" version="1">
+ <description summary="the lease object itself">
+ This interface represents the lease object and encapsulates the lease
+ properties. This objected is sent by zwp_kms_lease_request_v1::created
+ event. Use this object to retrieve lease properties.
+ </description>
+
+ <request name="destroy" type="destructor">
+ <description summary="destroys the temporary lease request object">
+ This has no effect on any remaining objects created through this
+ interface.
+ </description>
+ </request>
+
+ <request name="get_lease_info">
+ <description summary="request to retrieve info about the lease">
+ Request to retrieve lease information, like leased fd, monitor
+ and connector name.
+ </description>
+ </request>
+
+ <event name="lease_info">
+ <description summary="returns information about the lease">
+ This event returns (among other information about the connector leased)
+ the leased fd which is required for modesetting or queying page flips.
+ The client can use the leased fd to find out DRM-related information
+ like connector, CRTC, and plane ID using drmModeGetLease(). Using that
+ information it can derive a suitable mode useful when performing modeset.
+ </description>
+ <arg name="leased_fd" type="fd" summary="leased fd" />
+ <arg name="conn_name" type="string" summary="connector name of the lease" />
+ <arg name="monitor_name" type="string" summary="monitor name" />
+ </event>
+ </interface>
+
+ <interface name="zwp_kms_lease_request_v1" version="1">
+ <description summary="lease request object">
+ This interface is used for managing zwp_kms_lease_v1 object. It is used
+ to create a zwp_kms_lease_v1 object (the actual lease object) and also to
+ revoke the lease.
+ </description>
+
+ <request name="destroy" type="destructor">
+ <description summary="destroys the lease request object">
+ This has no effect on any remaining objects created through this
+ interface.
+ </description>
+ </request>
+
+ <request name="create">
+ <description summary="create">
+ Create a lease using the connector output name received in zwp_kms_lease_manager_v1::connectors.
+ Any attempt to use an incorrect connector name will reswult in zwp_kms_lease_request_v1::failed.
+ </description>
+ <arg name="connector" type="string" summary="connector output name"/>
+ </request>
+
+ <request name="revoke">
+ <description summary="revoke">
+ Revoke the lease, using the zwp_kms_lease_v1 objected received in
+ zwp_kms_lease_request_v1::created event.
+ </description>
+ <arg name="lease_obj" type="object" interface="zwp_kms_lease_v1" summary="lease object to remove" />
+ </request>
+
+ <event name="created">
+ <description summary="lease created successfully">
+ This event indicates that the lease has been created. It provides a zwp_kms_lease_v1 object
+ used for retrieving the fd representing the lease.
+ </description>
+ <arg name="lease_obj" type="new_id" interface="zwp_kms_lease_v1" summary="the lease obj"/>
+ </event>
+
+ <event name="failed">
+ <description summary="lease could not be created">
+ This event indicates that the lease could not be created/revoked.
+ </description>
+ </event>
+
+ <event name="revoked">
+ <description summary="lease revoked successfully">
+ This event indicates that the lease has been revoked.
+ </description>
+ </event>
+
+ </interface>
+</protocol>
--
2.9.3
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