Description: Modesetting: do not stop on EnterVT when connectors have disapeared
 Because of hotpluggeable GPUs and DP-MST, it is possible that CRTCs, connectors, and encoders may appear/disappear at run time.
 Normally, we would receive a uevent coming from Linux's DRM subsystem, which would trigger the check for disappearing/appearing resources. However, this event is not received when X would not be master (another VT is selected, or the machine is suspended), and so, when gaining back control, the modesetting driver would try to re-set the modes on all the connectors, fail to do so because the kernel would reject it on the disappeared connectors, and graceful stop the X-Server.
 To fix the issue, this series splits the kms-checking code from the uevent handling into its own (exported) function called drmmode_update_kms_state. This function is then called from both the uevent-handling function, and on EnterVT right before restoring the modes. The second patch then prevents setting the mode on disconnected/missing connectors, and thus restoring a working X-Server.
Author: Martin Peres
Origin: upstream, https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/443
---
This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
--- a/hw/xfree86/drivers/modesetting/driver.c
+++ b/hw/xfree86/drivers/modesetting/driver.c
@@ -1801,6 +1801,8 @@
 
     SetMaster(pScrn);
 
+    drmmode_update_kms_state(&ms->drmmode);
+
     if (!drmmode_set_desired_modes(pScrn, &ms->drmmode, TRUE))
         return FALSE;
 
--- a/hw/xfree86/drivers/modesetting/drmmode_display.c
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
@@ -3438,6 +3438,7 @@
         xf86CrtcPtr crtc = config->crtc[c];
         drmmode_crtc_private_ptr drmmode_crtc = crtc->driver_private;
         xf86OutputPtr output = NULL;
+        drmmode_output_private_ptr drmmode_output;
         int o;
 
         /* Skip disabled CRTCs */
@@ -3462,6 +3463,11 @@
         if (!output)
             continue;
 
+        /* Make sure the connector is still backed by a KMS id */
+        drmmode_output = output->driver_private;
+        if (!drmmode_output->mode_output || drmmode_output->mode_output->connection == DRM_MODE_DISCONNECTED)
+            continue;
+
         /* Mark that we'll need to re-set the mode for sure */
         memset(&crtc->mode, 0, sizeof(crtc->mode));
         if (!crtc->desiredMode.CrtcHDisplay) {
@@ -3579,30 +3585,20 @@
     return TRUE;
 }
 
-#ifdef CONFIG_UDEV_KMS
 
 #define DRM_MODE_LINK_STATUS_GOOD       0
 #define DRM_MODE_LINK_STATUS_BAD        1
 
-static void
-drmmode_handle_uevents(int fd, void *closure)
+void
+drmmode_update_kms_state(drmmode_ptr drmmode)
 {
-    drmmode_ptr drmmode = closure;
     ScrnInfoPtr scrn = drmmode->scrn;
-    struct udev_device *dev;
     drmModeResPtr mode_res;
     xf86CrtcConfigPtr  config = XF86_CRTC_CONFIG_PTR(scrn);
     int i, j;
     Bool found = FALSE;
     Bool changed = FALSE;
 
-    while ((dev = udev_monitor_receive_device(drmmode->uevent_monitor))) {
-        udev_device_unref(dev);
-        found = TRUE;
-    }
-    if (!found)
-        return;
-
     /* Try to re-set the mode on all the connectors with a BAD link-state:
      * This may happen if a link degrades and a new modeset is necessary, using
      * different link-training parameters. If the kernel found that the current
@@ -3716,6 +3712,25 @@
 #undef DRM_MODE_LINK_STATUS_BAD
 #undef DRM_MODE_LINK_STATUS_GOOD
 
+#ifdef CONFIG_UDEV_KMS
+
+static void
+drmmode_handle_uevents(int fd, void *closure)
+{
+    drmmode_ptr drmmode = closure;
+    struct udev_device *dev;
+    Bool found = FALSE;
+
+    while ((dev = udev_monitor_receive_device(drmmode->uevent_monitor))) {
+        udev_device_unref(dev);
+        found = TRUE;
+    }
+    if (!found)
+        return;
+
+    drmmode_update_kms_state(drmmode);
+}
+
 #endif
 
 void
--- a/hw/xfree86/drivers/modesetting/drmmode_display.h
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.h
@@ -269,6 +269,7 @@
 extern Bool drmmode_set_desired_modes(ScrnInfoPtr pScrn, drmmode_ptr drmmode, Bool set_hw);
 extern Bool drmmode_setup_colormap(ScreenPtr pScreen, ScrnInfoPtr pScrn);
 
+extern void drmmode_update_kms_state(drmmode_ptr drmmode);
 extern void drmmode_uevent_init(ScrnInfoPtr scrn, drmmode_ptr drmmode);
 extern void drmmode_uevent_fini(ScrnInfoPtr scrn, drmmode_ptr drmmode);