[PATCH xserver] modesetting: Consume all available udev events at once

[Daniel Martin]

From: Daniel Martin <consume.noise at gmail.com>

We get multiple udev events for actions like docking a laptop into its
station or plugging a monitor to the station. By consuming as much
events as we can, we reduce the number of output re-evalutions.

I.e. having a Lenovo X250 in a ThinkPad Ultra Dock and plugging a
monitor to the station generates 5 udev events. Or having 2 monitors
attached to the station and docking the laptop generates 7 events.

It depends on the timing how many events can consumed at once.

Signed-off-by: Daniel Martin <consume.noise at gmail.com>
---
 hw/xfree86/drivers/modesetting/drmmode_display.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.c b/hw/xfree86/drivers/modesetting/drmmode_display.c
index 0d34ca1..eeccb82 100644
--- a/hw/xfree86/drivers/modesetting/drmmode_display.c
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
@@ -1944,16 +1944,19 @@ drmmode_handle_uevents(int fd, void *closure)
     drmModeResPtr mode_res;
     xf86CrtcConfigPtr  config = XF86_CRTC_CONFIG_PTR(scrn);
     int i, j;
-    Bool found;
+    Bool found = FALSE;
     Bool changed = FALSE;
 
-    dev = udev_monitor_receive_device(drmmode->uevent_monitor);
-    if (!dev)
+    while ((dev = udev_monitor_receive_device(drmmode->uevent_monitor))) {
+        udev_device_unref(dev);
+        found = TRUE;
+    }
+    if (!found)
         return;
 
     mode_res = drmModeGetResources(drmmode->fd);
     if (!mode_res)
-        goto out;
+        return;
 
     if (mode_res->count_crtcs != config->num_crtc) {
         ErrorF("number of CRTCs changed - failed to handle, %d vs %d\n", mode_res->count_crtcs, config->num_crtc);
@@ -2012,9 +2015,7 @@ drmmode_handle_uevents(int fd, void *closure)
 
 out_free_res:
     drmModeFreeResources(mode_res);
-out:
     RRGetInfo(xf86ScrnToScreen(scrn), TRUE);
-    udev_device_unref(dev);
 }
 #endif
 
-- 
2.6.2