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drm/atomic_helper: Disallow new modesets on unregistered connectors

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With the exception of modesets which would switch the DPMS state of a
connector from on to off, we want to make sure that we disallow all
modesets which would result in enabling a new monitor or a new mode
configuration on a monitor if the connector for the display in question
is no longer registered. This allows us to stop userspace from trying to
enable new displays on connectors for an MST topology that were just
removed from the system, without preventing userspace from disabling
DPMS on those connectors.

Changes since v5:
- Fix typo in comment, nothing else

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20181008232437.5571-2-lyude@redhat.com
(cherry picked from commit 4d80273976)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
This commit is contained in:
Lyude Paul 2018-10-08 19:24:30 -04:00 committed by Joonas Lahtinen
parent f2bfc71aee
commit e96550956f
1 changed files with 20 additions and 1 deletions
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21
drivers/gpu/drm/drm_atomic_helper.c
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@ -308,6 +308,26 @@ update_connector_routing(struct drm_atomic_state *state,
return 0;
}
crtc_state = drm_atomic_get_new_crtc_state(state,
new_connector_state->crtc);
/*
* For compatibility with legacy users, we want to make sure that
* we allow DPMS On->Off modesets on unregistered connectors. Modesets
* which would result in anything else must be considered invalid, to
* avoid turning on new displays on dead connectors.
*
* Since the connector can be unregistered at any point during an
* atomic check or commit, this is racy. But that's OK: all we care
* about is ensuring that userspace can't do anything but shut off the
* display on a connector that was destroyed after its been notified,
* not before.
*/
if (!READ_ONCE(connector->registered) && crtc_state->active) {
DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] is not registered\n",
connector->base.id, connector->name);
return -EINVAL;
}
funcs = connector->helper_private;
if (funcs->atomic_best_encoder)
@ -352,7 +372,6 @@ update_connector_routing(struct drm_atomic_state *state,
set_best_encoder(state, new_connector_state, new_encoder);
crtc_state = drm_atomic_get_new_crtc_state(state, new_connector_state->crtc);
crtc_state->connectors_changed = true;
DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d:%s]\n",