From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13D6EC433F5 for ; Tue, 24 May 2022 10:55:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236430AbiEXKza (ORCPT ); Tue, 24 May 2022 06:55:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236424AbiEXKz2 (ORCPT ); Tue, 24 May 2022 06:55:28 -0400 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E81BA70906 for ; Tue, 24 May 2022 03:55:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1653389727; x=1684925727; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=e02kOghg8fnq2Pvf8EPQ0+8r8NY13VDEsJfrDbmJHYM=; b=K68yf2cRcX2uuG94OPDe5bgG/1BsO4AiSLbJE8foEatJu+Ix3IzZcTZh 2E6nzO9JMllu+nbitioof7Q7YvV9WexHbjqYAKHZX7hUIwMENmLqUtq5F /7QrZSiXvfFEe2pz1Ou7JwH8geBL1+zVJfNfXfasVvdqQPegRdaty6SGJ wlpRJsdAlFHd3u8Hm4aHB7frmSpkhD+WZilut4O7s05cygyKQQf8jgQwX 9JYpqON9Pyvb4voMSSskh4XSIN+6kAtSaZQop3558aI+4CpWEw3yG38l9 mxdYGpKXmZnTc9U6RgeAKgNTiXv17o/5A3nQCtNVLvT5kFqH58q+mnt8r Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10356"; a="253370432" X-IronPort-AV: E=Sophos;i="5.91,248,1647327600"; d="scan'208";a="253370432" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 May 2022 03:55:26 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,248,1647327600"; d="scan'208";a="717122071" Received: from kuha.fi.intel.com ([10.237.72.185]) by fmsmga001.fm.intel.com with SMTP; 24 May 2022 03:55:24 -0700 Received: by kuha.fi.intel.com (sSMTP sendmail emulation); Tue, 24 May 2022 13:55:23 +0300 Date: Tue, 24 May 2022 13:55:23 +0300 From: Heikki Krogerus To: Stefan Hoffmeister Cc: linux-usb@vger.kernel.org, Mika Westerberg Subject: Re: Thunderbolt: One missing DisplayPort? Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org +Mika On Fri, May 20, 2022 at 12:22:50PM +0200, Stefan Hoffmeister wrote: > I am trying to diagnose a problem where I get video output on > Thunderbolt on one DisplayPort, but no output on the second > DisplayPort. > > I would love to turn on all the (kernel-level) logging output that > there is, but do not know how to do that. > > Basically, on a Dell Inspiron 16 Plus (7610) laptop with Thunderbolt > 4, I am running Fedora Linux 36 with kernel 5.17+. > > Connecting that laptop to a Thunderbolt docking station (Intel > Thunderbolt 3 chip inside), > with two screens attached via DisplayPort, I get only one screen up and running. > > I'd like to discover more about this apparent error mode, because > attaching a different TB3 > setup works fine. I am looking for some means to enable logging or to > get debugging insight. > > Generally speaking, I suspect that this specific Dell laptop > (configuration) has some challenges > in the BIOS, and with Thunderbolt in general, but am totally blind to > what is going on. > > This system offers potential for fun, this being a hybrid PRIME > configuration, with an Intel iGPU passing through to an Nvidia dGPU > which seems to be the only wired-up way to get DisplayPort output. -- heikki