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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 D5B6BC433B4 for ; Wed, 19 May 2021 11:59:55 +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 8D78E60E0B for ; Wed, 19 May 2021 11:59:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D78E60E0B 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 BBD626ED83; Wed, 19 May 2021 11:59:54 +0000 (UTC) Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by gabe.freedesktop.org (Postfix) with ESMTPS id 022D46ED83 for ; Wed, 19 May 2021 11:59:52 +0000 (UTC) Received: from [IPv6:2804:431:e7dd:20a5:77af:59ad:49dc:ab16] (unknown [IPv6:2804:431:e7dd:20a5:77af:59ad:49dc:ab16]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: leandrohrb) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id B185B1F42717; Wed, 19 May 2021 12:59:50 +0100 (BST) Subject: Re: [PATCH 1/2] drm/doc: document how userspace should find out CRTC index To: Pekka Paalanen References: <20210428213651.55467-1-leandro.ribeiro@collabora.com> <20210428213651.55467-2-leandro.ribeiro@collabora.com> <20210506115053.15741550@eldfell> <20210512160422.66f3be04@eldfell> From: Leandro Ribeiro Message-ID: <5df41230-746a-1ab7-f6af-6a6cb6d6d872@collabora.com> Date: Wed, 19 May 2021 08:59:46 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210512160422.66f3be04@eldfell> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit 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: airlied@linux.ie, kernel@collabora.com, dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 5/12/21 10:04 AM, Pekka Paalanen wrote: > On Wed, 12 May 2021 09:50:14 -0300 > Leandro Ribeiro wrote: > >> On 5/6/21 5:50 AM, Pekka Paalanen wrote: >>> On Wed, 28 Apr 2021 18:36:50 -0300 >>> Leandro Ribeiro wrote: >>> >>>> In this patch we add a section to document what userspace should do to >>>> find out the CRTC index. This is important as there are multiple places >>>> in the documentation that need this, so it's better to just point to >>>> this section and avoid repetition. >>>> >>>> Signed-off-by: Leandro Ribeiro >>>> --- >>>> Documentation/gpu/drm-uapi.rst | 14 ++++++++++++++ >>>> drivers/gpu/drm/drm_debugfs_crc.c | 9 +++++---- >>>> include/uapi/drm/drm.h | 3 ++- >>>> 3 files changed, 21 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst >>>> index 04bdc7a91d53..1aa52a6ac567 100644 >>>> --- a/Documentation/gpu/drm-uapi.rst >>>> +++ b/Documentation/gpu/drm-uapi.rst >>>> @@ -457,6 +457,20 @@ Userspace API Structures >>>> .. kernel-doc:: include/uapi/drm/drm_mode.h >>>> :doc: overview >>>> >>>> +.. _crtc_index: >>>> + >>>> +CRTC index >>>> +---------- >>>> + >>>> +In some situations, it is important for userspace to find out the index of a >>> >>> That could be said about everything, so this sentence has no >>> information value. Instead, you could start by stating that CRTCs have >>> both an object ID and an index, and they are not the same thing. CRTC >>> index is used in cases where a densely packed identifier for a CRTC is >>> needed, e.g. in bit-for-crtc masks, where using the object ID would not >>> work. >>> >>>> +CRTC. The CRTC index should not be confused with its object id. >>>> + >>>> +In order to do this, userspace should first query the resources object >>> >>> Instead of saying what userspace must do, you could just explain where >>> it can be observed. >>> >>>> +from the device that owns the CRTC (using the DRM_IOCTL_MODE_GETRESOURCES >>> >>> So here you might start with: DRM_IOCTL_MODE_GETRESOURCES populates a >>> structure with an array of CRTC IDs. CRTC's index is its index in that >>> array. >>> >>>> +ioctl). The resources object contains a pointer to an array of CRTC's, and also >>>> +the number of entries of the array. The index of the CRTC is the same as its >>>> +position in this array. >>> >>> Anyway, the idea here is right. >>> >> >> So what about: >> >> CRTC's have both an object ID and an index, and they should not be >> confused. The index is used in cases where a densely packed identifier >> for a CRTC is needed, for instance in a bitmask of CRTC's. (maybe a link >> to the possible_crtcs field of struct drm_mode_get_plane? as example) >> >> DRM_IOCTL_MODE_GETRESOURCES populates a structure with an array of CRTC >> id's, and the CRTC index is its position in this array. > > Sure, sounds good. > > Capitalized 'ID'? > Sure, I'll add this change. Thanks, Leandro