drm/display/dp_mst: Add nonblocking helpers for DP MST
As Daniel Vetter pointed out, if we only use the atomic modesetting locks with MST it's technically possible for a driver with non-blocking modesets to race when it comes to MST displays - as we make the mistake of not doing our own CRTC commit tracking in the topology_state object. This could potentially cause problems if something like this happens: * User starts non-blocking commit to disable CRTC-1 on MST topology 1 * User starts non-blocking commit to enable CRTC-2 on MST topology 1 There's no guarantee here that the commit for disabling CRTC-2 will only occur after CRTC-1 has finished, since neither commit shares a CRTC - only the private modesetting object for MST. Keep in mind this likely isn't a problem for blocking modesets, only non-blocking. So, begin fixing this by keeping track of which CRTCs on a topology have changed by keeping track of which CRTCs we release or allocate timeslots on. As well, add some helpers for: * Setting up the drm_crtc_commit structs in the ->commit_setup hook * Waiting for any CRTC dependencies from the previous topology state v2: * Use drm_dp_mst_atomic_setup_commit() directly - Jani Signed-off-by: Lyude Paul <lyude@redhat.com> Cc: Wayne Lin <Wayne.Lin@amd.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Fangzhi Zuo <Jerry.Zuo@amd.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Imre Deak <imre.deak@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Sean Paul <sean@poorly.run> Acked-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220817193847.557945-9-lyude@redhat.com
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