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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0EE97C43461 for ; Mon, 7 Sep 2020 11:32:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D1C0121481 for ; Mon, 7 Sep 2020 11:32:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729059AbgIGLc0 (ORCPT ); Mon, 7 Sep 2020 07:32:26 -0400 Received: from bmailout3.hostsharing.net ([176.9.242.62]:60477 "EHLO bmailout3.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728993AbgIGLcV (ORCPT ); Mon, 7 Sep 2020 07:32:21 -0400 X-Greylist: delayed 586 seconds by postgrey-1.27 at vger.kernel.org; Mon, 07 Sep 2020 07:32:20 EDT Received: from h08.hostsharing.net (h08.hostsharing.net [83.223.95.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.hostsharing.net", Issuer "COMODO RSA Domain Validation Secure Server CA" (not verified)) by bmailout3.hostsharing.net (Postfix) with ESMTPS id CC550100DA1AF; Mon, 7 Sep 2020 13:21:51 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 8E6881FB9D; Mon, 7 Sep 2020 13:21:51 +0200 (CEST) Date: Mon, 7 Sep 2020 13:21:51 +0200 From: Lukas Wunner To: Mika Westerberg Cc: linux-usb@vger.kernel.org, Michael Jamet , Yehezkel Bernat , Andreas Noever , Kai-Heng Feng Subject: Re: [PATCH] thunderbolt: Retry DROM read once if parsing fails Message-ID: <20200907112151.GA22115@wunner.de> References: <20200907110340.71031-1-mika.westerberg@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200907110340.71031-1-mika.westerberg@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Mon, Sep 07, 2020 at 02:03:40PM +0300, Mika Westerberg wrote: > Kai-Heng reported that sometimes DROM parsing of ASUS PA27AC Thunderbolt 3 > monitor fails. This makes the driver to fail to add the device so only > DisplayPort tunneling is functional. Maybe the DROM is contained in an external EEPROM attached via slow SPI or i2c and cannot be read in time before a response on the control channel is due? Does it help to always delay 100 ms before performing the DROM read with this display? Perhaps a quirk specific for this display is more appropriate than a change which affects all devices? Because this way of working around problems is difficult to maintain long term. Thanks, Lukas