[PATCH wayland-protocols v3] unstable/drm-lease: DRM lease protocol support
Philipp Zabel
p.zabel at pengutronix.de
Wed Aug 22 07:17:50 UTC 2018
Hi Marius,
On Mon, 2018-08-20 at 23:00 +0300, Marius Vlad wrote:
> 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.
Why not just send the connectors one by one, a single event with all
relevant information for each?
Especially EDID info would be most useful for finding the right VR
headset.
> 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.
Can't the client query available modes on the passed connector via the
leased fd?
> A server/client implementation to match this protocol
> can be found at https://gitlab.freedesktop.org/marius.vlad0/weston/commits/new-drm-lease
This crashed for me in drm_lease_manager_create_lease_req with a NULL
pointer dereference because head->output == NULL for an unconnected
head.
Also I noticed zwm_kms_lease_request_v1_implementation is missing the
.destroy request callback.
> 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">
There's a level of indentation is missing from here.
> + <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>
regards
Philipp
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