Re: Protectli FW1 with Intel 82583V - Interfaces errors and latency spike issue

I tested with a Protectli FW1 router (dmesg below) forwarding packets
between two test machines. The latency spikes occur when running
headless beginning with this commit:

commit 78cd60329a9b42e2a8e91bb88c3d556b4e420e89
Author: jsg <jsg@openbsd.org>
Date: Mon Sep 9 01:35:43 2019 +0000

When no display outputs are connected on boot linux 4.19 drm relies
on
deferred setup to handle the console framebuffer where as linux 4.4
drm
created a 1024x768 console framebuffer in this situation.

As we only handle setting up rasops and wsdisplay on attach go back
to
the old behaviour for now so a display can be connected after
booting
with none attached to interact with the console.

This partly reverts linux commit
drm/fb-helper: Support deferred setup
ca91a2758fcef6635626993557dd51cfbb6dd134

Reported and tested by Marcus MERIGHI.
Tested by and ok kettenis@

diff --git sys/dev/pci/drm/drm_fb_helper.c
sys/dev/pci/drm/drm_fb_helper.c
index 8e134187f6c..d95b8acbebd 100644
--- sys/dev/pci/drm/drm_fb_helper.c
+++ sys/dev/pci/drm/drm_fb_helper.c
@@ -2002,15 +2002,23 @@ static int drm_fb_helper_single_fb_probe(struct
drm_fb_helper *fb_helper,
}

if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height
== -1) {
+#ifdef __linux__
DRM_INFO("Cannot find any crtc or sizes\n");

/* First time: disable all crtc's.. */
-#ifdef notyet
/* XXX calling this hangs boot with no connected outputs
*/
if (!fb_helper->deferred_setup /* &&
SPLAY_EMPTY(fb_helper->dev->files) */)
restore_fbdev_mode(fb_helper);
-