NetBSD Problem Report #54026

From  Thu Feb 28 21:04:03 2019
Return-Path: <>
Received: from ( [])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(Client CN "", Issuer " CA" (not verified))
	by (Postfix) with ESMTPS id 9DB3F7A16B
	for <>; Thu, 28 Feb 2019 21:04:03 +0000 (UTC)
Message-Id: <>
Date: Thu, 28 Feb 2019 21:04:02 +0000 (UTC)
Subject: simplefb fails to sync with 4K monitor
X-Send-Pr-Version: www-1.0

>Number:         54026
>Category:       port-evbarm
>Synopsis:       simplefb fails to sync with 4K monitor
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-evbarm-maintainer
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 28 21:05:00 +0000 2019
>Closed-Date:    Sat Oct 29 14:18:12 +0000 2022
>Last-Modified:  Sat Oct 29 14:18:12 +0000 2022
>Originator:     Benny Siegert
>Release:        NetBSD 8.99.34 (as of 2019-02-26)
The NetBSD Foundation
NetBSD arm64 8.99.34 NetBSD 8.99.34 (GENERIC) #0: Tue Feb 26 15:55:33 UTC 2019 evbarm
I had this with two machines, an Orange Pi Plus 2E (32 bits) and a Pine A64-LTS (64 bits). The monitor is a Dell P2415Q (4K), connected via HDMI 1.4, so its preferred resolution is 3840x2160 at 30Hz.

During U-Boot (and NetBSD boot), the picture appears OK, but as soon as the NetBSD kernel takes over, the screen loses sync. The picture re-appears for less than a second, then a black screen again. After a while, the monitor displays an error ("current timing is unsupported") and switches off.

If you boot with "nomodeset" on the kernel command line, you get the desired resolution with no flicker.
Boot NetBSD/evbarm on a 4K screen connected via HDMI.



State-Changed-From-To: open->feedback
State-Changed-When: Sat, 14 May 2022 20:07:00 +0000
Please provide serial logs / dmesg from when the screen loses sync.

State-Changed-From-To: feedback->closed
State-Changed-When: Sat, 29 Oct 2022 14:18:12 +0000
Feedback timeout.


NetBSD Home
NetBSD PR Database Search

(Contact us) $NetBSD: query-full-pr,v 1.47 2022/09/11 19:34:41 kim Exp $
$NetBSD:,v 1.9 2014/08/02 14:16:04 spz Exp $
Copyright © 1994-2022 The NetBSD Foundation, Inc. ALL RIGHTS RESERVED.