From patchwork Tue Sep 10 10:09:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Simon Ser X-Patchwork-Id: 11139151 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9904976 for ; Tue, 10 Sep 2019 10:10:09 +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 9F9972067B for ; Tue, 10 Sep 2019 10:10:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F9972067B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=emersion.fr 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 31F056E02B; Tue, 10 Sep 2019 10:10:07 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail2.protonmail.ch (mail2.protonmail.ch [185.70.40.22]) by gabe.freedesktop.org (Postfix) with ESMTPS id D05F26E02B for ; Tue, 10 Sep 2019 10:10:05 +0000 (UTC) Date: Tue, 10 Sep 2019 10:09:55 +0000 To: dri-devel@lists.freedesktop.org From: Simon Ser Subject: [PATCH] drm: two planes with the same zpos have undefined ordering Message-ID: Feedback-ID: FsVprHBOgyvh0T8bxcZ0CmvJCosWkwVUg658e_lOUQMnA9qynD8O1lGeniuBDfPSkDAUuhiKfOIXUZBfarMyvA==:Ext:ProtonMail MIME-Version: 1.0 X-Spam-Status: No, score=-1.2 required=7.0 tests=ALL_TRUSTED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on mail.protonmail.ch X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=emersion.fr; s=protonmail; t=1568110203; bh=pLcs3TZTeMmGkKU5PLXsaMqGRuSBRvvwKGFmGE8qCzI=; h=Date:To:From:Cc:Reply-To:Subject:Feedback-ID:From; b=hC4keIgezkPUPCMmV6BRSEtF1CNCdz0pbQSbuUc08bB2yxniPcFVXezsZtL4OJUuR TSHC1Bz9KvxDzjo0/ZIAYN0mCTuH6WswsHdXOkUtmDDWBv3HZVJxSF1OjGrOWVEbpT BaMOfif87+J+ZGvd1CXQvPs/+11plhD7n3gXKgDQ= X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Simon Ser Cc: daniel.vetter@ffwll.ch, pekka.paalanen@collabora.com, daniels@collabora.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Currently the property docs don't specify whether it's okay for two planes to have the same zpos value and what user-space should expect in this case. The rule mentionned in the past was to disambiguate with object IDs. However some drivers break this rule (that's why the ordering is documented as unspecified in case the zpos property is missing). Additionally it doesn't really make sense for a driver to user identical zpos values if it knows their relative position: the driver can just pick different values instead. So two solutions would make sense: either disallow completely identical zpos values for two different planes, either make the ordering unspecified. To allow drivers that don't know the relative ordering between two planes to still expose the zpos property, choose the latter solution. Signed-off-by: Simon Ser --- Err, I'm sorry about the double-post. I sent this to intel-gfx by mistake. drivers/gpu/drm/drm_blend.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) -- 2.23.0 diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c index d02709dd2d4a..51bd5454e50a 100644 --- a/drivers/gpu/drm/drm_blend.c +++ b/drivers/gpu/drm/drm_blend.c @@ -132,10 +132,10 @@ * planes. Without this property the primary plane is always below the cursor * plane, and ordering between all other planes is undefined. The positive * Z axis points towards the user, i.e. planes with lower Z position values - * are underneath planes with higher Z position values. Note that the Z - * position value can also be immutable, to inform userspace about the - * hard-coded stacking of overlay planes, see - * drm_plane_create_zpos_immutable_property(). + * are underneath planes with higher Z position values. Two planes with the + * same Z position value have undefined ordering. Note that the Z position + * value can also be immutable, to inform userspace about the hard-coded + * stacking of overlay planes, see drm_plane_create_zpos_immutable_property(). * * pixel blend mode: * Pixel blend mode is set up with drm_plane_create_blend_mode_property().