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=-10.4 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 43AF3C433E6 for ; Fri, 26 Feb 2021 12:10:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EAF4464ED2 for ; Fri, 26 Feb 2021 12:10:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229545AbhBZMKR (ORCPT ); Fri, 26 Feb 2021 07:10:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229526AbhBZMKR (ORCPT ); Fri, 26 Feb 2021 07:10:17 -0500 Received: from smtp.domeneshop.no (smtp.domeneshop.no [IPv6:2a01:5b40:0:3005::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD3D6C061574 for ; Fri, 26 Feb 2021 04:09:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tronnes.org ; s=ds202012; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:References:Cc:To:From:Subject:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=069mkm7tqItUG64Ib7wUtneTZFgWoa3IFZJXAvEdDLw=; b=dLfKwVJh7zQUEaYCNBkkubHqqr ktYyAfOJhtunI4nYnifVe4V5LgzTWkZeQujkEhMpOcxOyUh5aL2E9H4UNKk5yz3bzJKG/KAgB0djH 3T4oB1NeEpJDYReVt0iDNm4AY8cqyt4TF1ePmSlTA/kJ+aovs8QSAOIGx1o2/57qoWw0+zlZZse2R vsg4BPJbhQc5PojOwsbvPt0/FdWRe4TuAC1HzrULRL1qzWYkNNDW6mkAjFHUJ7DUZk6SgXn4ZiwDp M41saTuaKFIz575OJcR6ILGnZxsWyH0uG/6vV2+dRrWxObfNjPfHScffIPcTsmFrcM8/+OQpu+kZl 0PkEbyig==; Received: from 211.81-166-168.customer.lyse.net ([81.166.168.211]:65161 helo=[192.168.10.61]) by smtp.domeneshop.no with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1lFbvr-0007hf-M6; Fri, 26 Feb 2021 13:09:19 +0100 Subject: Re: [PATCH v6 3/3] drm: Add GUD USB Display driver From: =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= To: Peter Stuge Cc: hudson@trmm.net, markus@raatikainen.cc, Daniel Vetter , linux-usb@vger.kernel.org, dri-devel@lists.freedesktop.org, th020394@gmail.com, lkundrak@v3.sk, pontus.fuchs@gmail.com, sam@ravnborg.org References: <20210219121702.50964-1-noralf@tronnes.org> <20210219121702.50964-4-noralf@tronnes.org> <20210219214243.11330.qmail@stuge.se> <5c00a868-3a2f-438b-3670-ee86caef4d2a@tronnes.org> Message-ID: <3ee3fad6-61be-b848-a68f-df7c2e0001f9@tronnes.org> Date: Fri, 26 Feb 2021 13:09:15 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <5c00a868-3a2f-438b-3670-ee86caef4d2a@tronnes.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Den 20.02.2021 18.27, skrev Noralf Trønnes: > > > Den 19.02.2021 22.42, skrev Peter Stuge: >> >> More generally it's not very typical in USB to report the data size >> separately from the data itself, if reporting size explicitly at all. >> >> Sizes can be part of the data structure itself (like in descriptors) but >> on the application layer (like here) it's convenient to just decide a >> sensible fixed maximum size and let the host try to always transfer >> that size while accepting short transfers. Unlike read() a short >> transfer only ever happens if and when a device intends for it, >> so that's like an in-band handshake but "for free". >> >> Oh, and does/should the GUD EDID change if the panel "behind" the device >> CPU on a hotpluggable connector changes? It wouldn't be great to require >> GUD driver reprobe in that case. But maybe DRM requires that anyway? >> > > If gud_connector_status_req.status has changed since last poll or > GUD_CONNECTOR_STATUS_CHANGED is set, DRM will notify userspace which > will reprobe the connector. connector->epoch_counter++ in > gud_connector_status_request() triggers that. > >> >> I'm sorry I didn't spot this pattern earlier, I understand that it's late >> in the game and that changing it needs the gadget to change as well, but I >> do really think this is a worthwhile change throughout the protocol. >> > > I see what you mean, I'll give it a try. > Peter, please have a look at this diff and see if I'm on the right track here: https://gist.github.com/notro/a43a93a3aa0cc75d930890b7b254fc0a I want to avoid waisting a patch version cycle by being way off. Noralf.