[mutter] monitor-manager-xrandr: Set CRTC config even if it might be redundant

[Rui Matos <rtcm src gnome org>]

commit 5a86286aba3a513a14628d634db5f0ed327beead
Author: Rui Matos <tiagomatos gmail com>
Date:   Wed Dec 10 15:55:12 2014 +0100

    monitor-manager-xrandr: Set CRTC config even if it might be redundant
    
    This optimization breaks our use of XRRScreenResources' timestamps to
    detect hotplugs in case one of the outputs is disconnected and the
    remaining ones don't need any mode, position or transform adjustments.
    
    In that scenario, when applying the new configuration, we resize the X
    screen but never call XRRSetCrtcConfig() and since XRRSetScreenSize()
    doesn't take a timestamp and the X server doesn't update its last set
    timestamp, when we next get a RRScreenChangeNotify and update
    ourselves, XRRScreenResources.timestamp will still be smaller than
    XRRScreenResources.configTimestamp which makes us think we're seeing a
    new hotplug. We just don't enter an endless loop because the screen
    size that we keep applying is always the same and the X server
    short-circuits and stops sending us RRScreenChangeNotifys.
    
    Always calling XRRSetCrtcConfig() ensures that the last set timestamp
    will be bigger than configTimestamp in the next event and thus making
    us trigger the monitors-changed signal properly.
    
    Note that the X server already does basically the same checks that
    we're removing here, so doing this shouldn't be a significant
    efficiency loss. See
    
    http://cgit.freedesktop.org/xorg/xserver/tree/randr/rrcrtc.c?h=server-1.16-branch#n539

 src/backends/x11/meta-monitor-manager-xrandr.c |   25 ------------------------
 1 files changed, 0 insertions(+), 25 deletions(-)
---
diff --git a/src/backends/x11/meta-monitor-manager-xrandr.c b/src/backends/x11/meta-monitor-manager-xrandr.c
index dd32bd4..7a3926f 100644
--- a/src/backends/x11/meta-monitor-manager-xrandr.c
+++ b/src/backends/x11/meta-monitor-manager-xrandr.c
@@ -888,26 +888,12 @@ meta_monitor_manager_xrandr_apply_configuration (MetaMonitorManager *manager,
           unsigned int j, n_outputs;
           int width, height;
           Status ok;
-          unsigned long old_controlled_mask;
-          unsigned long new_controlled_mask;
 
           mode = crtc_info->mode;
 
           n_outputs = crtc_info->outputs->len;
           outputs = g_new (XID, n_outputs);
 
-          old_controlled_mask = 0;
-          for (j = 0; j < manager->n_outputs; j++)
-            {
-              MetaOutput *output;
-
-              output = &manager->outputs[j];
-
-              if (output->crtc == crtc)
-                old_controlled_mask |= 1UL << j;
-            }
-
-          new_controlled_mask = 0;
           for (j = 0; j < n_outputs; j++)
             {
               MetaOutput *output;
@@ -916,21 +902,10 @@ meta_monitor_manager_xrandr_apply_configuration (MetaMonitorManager *manager,
 
               output->is_dirty = TRUE;
               output->crtc = crtc;
-              new_controlled_mask |= 1UL << j;
 
               outputs[j] = output->winsys_id;
             }
 
-          if (crtc->current_mode == mode &&
-              crtc->rect.x == crtc_info->x &&
-              crtc->rect.y == crtc_info->y &&
-              crtc->transform == crtc_info->transform &&
-              old_controlled_mask == new_controlled_mask)
-            {
-              /* No change */
-              goto next;
-            }
-
           ok = XRRSetCrtcConfig (manager_xrandr->xdisplay,
                                  manager_xrandr->resources,
                                  (XID)crtc->crtc_id,