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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 E5B47C32771 for ; Mon, 6 Jan 2020 07:41:37 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B725821775 for ; Mon, 6 Jan 2020 07:41:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B725821775 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3911C89BBE; Mon, 6 Jan 2020 07:41:37 +0000 (UTC) Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4366189BBE for ; Mon, 6 Jan 2020 07:41:36 +0000 (UTC) Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id AC99928A0EC; Mon, 6 Jan 2020 07:41:34 +0000 (GMT) Date: Mon, 6 Jan 2020 08:41:31 +0100 From: Boris Brezillon To: Andrzej Hajda , Marek Szyprowski Subject: Re: [PATCH 3/3] drm/exynos: dsi: Fix bridge chain handling Message-ID: <20200106084131.0d4a8002@collabora.com> In-Reply-To: <20191227144124.210294-3-boris.brezillon@collabora.com> References: <20191227144124.210294-1-boris.brezillon@collabora.com> <20191227144124.210294-3-boris.brezillon@collabora.com> Organization: Collabora X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jernej Skrabec , Jonas Karlman , Neil Armstrong , Seung-Woo Kim , dri-devel@lists.freedesktop.org, Kyungmin Park , Laurent Pinchart Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, 27 Dec 2019 15:41:24 +0100 Boris Brezillon wrote: > Commit 05193dc38197 ("drm/bridge: Make the bridge chain a double-linked > list") patched the bridge chain logic to use a double-linked list instead > of a single-linked list. This change induced changes to the Exynos driver > which was manually resetting the encoder->bridge element to NULL to > control the enable/disable sequence of the bridge chain. During this > conversion, 2 bugs were introduced: > > 1/ list_splice() was used to move chain elements to our own internal > chain, but list_splice() does not reset the source list to an empty > state, leading to unexpected bridge hook calls when > drm_bridge_chain_xxx() helpers were called by the core. Replacing > the list_splice() call by list_splice_init() fixes this problem. > > 2/ drm_bridge_chain_xxx() helpers operate on the > bridge->encoder->bridge_chain list, which is now empty. When the > helper uses list_for_each_entry_reverse() we end up with no operation > done which is not what we want. But that's even worse when the helper > uses list_for_each_entry_from(), because in that case we end up in > an infinite loop searching for the list head element which is no > longer encoder->bridge_chain but exynos_dsi->bridge_chain. To address > that problem we stop using the bridge chain helpers and call the > hooks directly. > > Reported-by: Marek Szyprowski > Fixes: 05193dc38197 ("drm/bridge: Make the bridge chain a double-linked list") > Signed-off-by: Boris Brezillon > --- > Hello Marek, > > I'm perfectly fine applying your patch instead of this one if you prefer > to restrict the logic to a single bridge per chain. I just sent this > patch in case your okay with the slightly different version I propose > here. Marek, Andrzej, did you have time to look at this patch (or respin "drm/bridge: Fix Exynos DSI after making bridge chain a double-linked list" if you don't like this version)? I'd really like to apply this fix (and its vc4 equivalent) to drm-misc-next as soon as possible. Thanks, Boris _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel