| Message ID | 20220712033246.1148476-9-zack@kde.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix cursor planes with virtualized drivers | expand |
On Tuesday, July 12th, 2022 at 05:32, Zack Rusin <zack@kde.org> wrote:
> To do that introduce DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE
Nit: maybe we can name this "DRM_CLIENT_CAP_VIRTUAL_CURSOR_PLANE" or
even "DRM_CLIENT_CAP_VIRTUAL_CURSORS", since "CAP" already implies that
this is a capability that the DRM client supports.
On Mon, 11 Jul 2022 23:32:46 -0400 Zack Rusin <zack@kde.org> wrote: > From: Zack Rusin <zackr@vmware.com> > > Virtualized drivers place additional restrictions on the cursor plane > which breaks the contract of universal planes. To allow atomic > modesettings with virtualized drivers the clients need to advertise > that they're capable of dealing with those extra restrictions. > > To do that introduce DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE which > lets DRM know that the client is aware of and capable of dealing with > the extra restrictions on the virtual cursor plane. > > Setting this option to true makes DRM expose the cursor plane on > virtualized drivers. The userspace is expected to set the hotspots > and handle mouse events on that plane. > > Signed-off-by: Zack Rusin <zackr@vmware.com> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> > Cc: Maxime Ripard <mripard@kernel.org> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: David Airlie <airlied@linux.ie> > Cc: Daniel Vetter <daniel@ffwll.ch> > Cc: dri-devel@lists.freedesktop.org > --- > drivers/gpu/drm/drm_ioctl.c | 9 +++++++++ > include/uapi/drm/drm.h | 17 +++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c > index 8faad23dc1d8..f10590b061d7 100644 > --- a/drivers/gpu/drm/drm_ioctl.c > +++ b/drivers/gpu/drm/drm_ioctl.c > @@ -362,6 +362,15 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv) > return -EINVAL; > file_priv->writeback_connectors = req->value; > break; > + case DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE: > + if (!drm_core_check_feature(dev, DRIVER_VIRTUAL)) > + return -EOPNOTSUPP; Ah! Is userspace expected to use this EOPNOTSUPP error to tell virtual cursor planes apart from generic hardware planes that were just tagged as cursor? I am thinking about how an atomic KMS client can do both: - use generic cursor plane for generic content, and - use a virtual cursor plane correctly One possibility here is for the atomic KMS client: - try to set DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE - if it succeeds, all cursor planes it can see are virtual - if it fails, all cursor planes it can see are generic That sounds good to me, because I don't think the same DRM device would want to expose both kinds of cursor planes. However, this should be added in the DRM documentation facing userspace. > + if (!file_priv->atomic) > + return -EINVAL; > + if (req->value > 1) > + return -EINVAL; > + file_priv->supports_virtual_cursor_plane = req->value; > + break; > default: > return -EINVAL; > } > diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h > index 642808520d92..f24a1941abca 100644 > --- a/include/uapi/drm/drm.h > +++ b/include/uapi/drm/drm.h > @@ -836,6 +836,23 @@ struct drm_get_cap { > */ > #define DRM_CLIENT_CAP_WRITEBACK_CONNECTORS 5 > > +/** > + * DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE > + * > + * If set to 1, the DRM core will expose cursor plane to be used for > + * virtualized mouse cursor, without virtualized drivers will not expose > + * the cursor plane in atomic contexts. Cursor planes in virtualized I would suggest some re-wording here, because at first I read this like: Without virtualized drivers, setting this cap will hide all cursor planes from userspace. It's also a bit unclear on what happens when userspace sets this cap on a non-virtual driver. From the code I see that it will fail, but that might be a surprise to userspace developers. I suppose explaining the virtual vs. generic cursor plane detection will address this. > + * drivers come with some additional restrictions and are not truly > + * universal, e.g. they need to act like one would expect from a mouse > + * cursor and have correctly set hotspot properties. > + * The client must enable &DRM_CLIENT_CAP_ATOMIC first. > + * > + * This capability is always supported for atomic-capable virtualized drivers > + * starting from kernel version 5.21. > + */ > +#define DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE 6 > + > + > /* DRM_IOCTL_SET_CLIENT_CAP ioctl argument type */ > struct drm_set_client_cap { > __u64 capability; Thanks, pq
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 8faad23dc1d8..f10590b061d7 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -362,6 +362,15 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv) return -EINVAL; file_priv->writeback_connectors = req->value; break; + case DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE: + if (!drm_core_check_feature(dev, DRIVER_VIRTUAL)) + return -EOPNOTSUPP; + if (!file_priv->atomic) + return -EINVAL; + if (req->value > 1) + return -EINVAL; + file_priv->supports_virtual_cursor_plane = req->value; + break; default: return -EINVAL; } diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index 642808520d92..f24a1941abca 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -836,6 +836,23 @@ struct drm_get_cap { */ #define DRM_CLIENT_CAP_WRITEBACK_CONNECTORS 5 +/** + * DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE + * + * If set to 1, the DRM core will expose cursor plane to be used for + * virtualized mouse cursor, without virtualized drivers will not expose + * the cursor plane in atomic contexts. Cursor planes in virtualized + * drivers come with some additional restrictions and are not truly + * universal, e.g. they need to act like one would expect from a mouse + * cursor and have correctly set hotspot properties. + * The client must enable &DRM_CLIENT_CAP_ATOMIC first. + * + * This capability is always supported for atomic-capable virtualized drivers + * starting from kernel version 5.21. + */ +#define DRM_CLIENT_CAP_SUPPORTS_VIRTUAL_CURSOR_PLANE 6 + + /* DRM_IOCTL_SET_CLIENT_CAP ioctl argument type */ struct drm_set_client_cap { __u64 capability;