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=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 F29C6C43387 for ; Mon, 17 Dec 2018 09:32:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A99F206A2 for ; Mon, 17 Dec 2018 09:32:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="la+VeiBr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732031AbeLQJcQ (ORCPT ); Mon, 17 Dec 2018 04:32:16 -0500 Received: from mail-ed1-f65.google.com ([209.85.208.65]:42893 "EHLO mail-ed1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731578AbeLQJcP (ORCPT ); Mon, 17 Dec 2018 04:32:15 -0500 Received: by mail-ed1-f65.google.com with SMTP id y20so3976331edw.9 for ; Mon, 17 Dec 2018 01:32:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=sender:date:from:to:cc:subject:message-id:mail-followup-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=aduliYsUMI6GJw8p5hCn2zCF/bHY+v2DYc9RtAhZpiI=; b=la+VeiBrJ+CKTsO0sKSNDZyD/kJ78KK05TRwn0FX4cOJ35g/+LacdFOCoglFpWszik Q8aR+KxdKf+NqgW08JfuZpbiYrtxtj6fWGVcKKyf1N+/oUoXAv9aki6bzjrPmIeDp/vq RrKsFYtnnUnjELlg+qZtzRtbbQ2ch399vyOXc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to:user-agent; bh=aduliYsUMI6GJw8p5hCn2zCF/bHY+v2DYc9RtAhZpiI=; b=BElABwWirM9z8KsVbVS1cTLzczk/zqCjyeVtiGI4+BbOWTD2C92TWhs121y4I+0W+6 xO4ljDvh4RhxuI/peLhaAKv84cBOZzFiVPdYtc+4H5U2DzjlYL1/MItByIipnGHTcIX7 rqtj0H2Z6FSp3+SgCUg/usWs2FgJZnmCZiPzjlnCvNo2vPjUCC2Qr2K9+Ept23Wz8y0N N+jRVG4wg1TYopG83UW9yLWCzQxRB81F2nd3XolmNZigajvrVyWTbLUmJDtM8gfcleqb WJWwiIAKSVwHKICa6QwhfJE2ZXRRbB7kx811Sz79LLj6/6FZWIXlEBnuvmCxaywjcyx8 gqiw== X-Gm-Message-State: AA+aEWbOYs5BNrKzhxa/kb2+aC82k7he9rfTbQPPFtvXy7CKNQ33NJ/B oX2PjsujMCaprHiOg9Cjx5UveQ== X-Google-Smtp-Source: AFSGD/XmoMaYJMoFLIch/qmDC5B8fSyTDmZxMz/dw06gRIgoYdhGZOFnZteBNKyGafrwOfHDWF01nA== X-Received: by 2002:a50:903c:: with SMTP id b57mr12417237eda.161.1545039133292; Mon, 17 Dec 2018 01:32:13 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:569e:0:3106:d637:d723:e855]) by smtp.gmail.com with ESMTPSA id p22-v6sm1840456ejf.48.2018.12.17.01.32.11 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 17 Dec 2018 01:32:11 -0800 (PST) Date: Mon, 17 Dec 2018 10:32:09 +0100 From: Daniel Vetter To: Helen Koike Cc: Tomasz Figa , dnicoara@chromium.org, =?iso-8859-1?Q?St=E9phane?= Marchesin , Sean Paul , Alexandros Frantzis , David Airlie , Linux Kernel Mailing List , dri-devel , Gustavo Padovan , kernel@collabora.com Subject: Re: [PATCH v2] drm/atomic: add ATOMIC_AMEND flag to the Atomic IOCTL. Message-ID: <20181217093209.GX21184@phenom.ffwll.local> Mail-Followup-To: Helen Koike , Tomasz Figa , dnicoara@chromium.org, =?iso-8859-1?Q?St=E9phane?= Marchesin , Sean Paul , Alexandros Frantzis , David Airlie , Linux Kernel Mailing List , dri-devel , Gustavo Padovan , kernel@collabora.com References: <20181123215354.14540-1-helen.koike@collabora.com> <20181213090128.GB21184@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 4.18.0-2-amd64 User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 13, 2018 at 11:35:33PM -0200, Helen Koike wrote: > Hello, > > On 12/13/18 7:01 AM, Daniel Vetter wrote: > > On Thu, Dec 13, 2018 at 04:43:57PM +0900, Tomasz Figa wrote: > >> Hi Helen, > >> > >> On Sat, Nov 24, 2018 at 6:54 AM Helen Koike wrote: > >>> > >>> This flag tells core to jump ahead the queued update if the conditions > >>> in drm_atomic_async_check() are met. That means we are only able to do an > >>> async update if no modeset is pending and update for the same plane is > >>> not queued. > >> > >> First of all, thanks for the patch. Please see my comments below. > >> > >> If the description above applies (and AFAICT that's what the existing > >> code does indeed), then this doesn't sound like "amend" to me. It > >> sounds exactly as the kernel code calls it - "async update" or perhaps > >> "instantaneous commit" could better describe it? > > There is an error in this patch (please, see below). > Async should fail if there is no pending commit, at least is what I > understand from the discussion at > https://patchwork.freedesktop.org/patch/243088/ Hm, that's not really my takeaway from that discussion. There's lots of open issues with this uapi (too many real-world corner cases that aren't thought through yet), but that conclusion I didn't find anywhere ... -Daniel > > >> > >>> > >>> It uses the already in place infrastructure for async updates. > >>> > >>> It is useful for cursor updates and async PageFlips over the atomic > >>> ioctl, otherwise in some cases updates may be delayed to the point the > >>> user will notice it. Note that for now it's only enabled for cursor > >>> planes. > >>> > >>> DRM_MODE_ATOMIC_AMEND should be passed to the Atomic IOCTL to use this > >>> feature. > >>> > >>> Signed-off-by: Gustavo Padovan > >>> Signed-off-by: Enric Balletbo i Serra > >>> [updated for upstream] > >>> Signed-off-by: Helen Koike > >>> --- > >>> Hi, > >>> > >>> This is the second attempt to introduce the new ATOMIC_AMEND flag for atomic > >>> operations, see the commit message for a more detailed description. > >>> > >>> This was tested using a small program that exercises the uAPI for easy > >>> sanity testing. The program was created by Alexandros and modified by > >>> Enric to test the capability flag [2]. > >>> > >>> To test, just build the program and use the --atomic flag to use the cursor > >>> plane with the ATOMIC_AMEND flag. E.g. > >>> > >>> drm_cursor --atomic > >>> > >>> The test worked on a rockchip Ficus v1.1 board on top of mainline plus > >>> the patch to update cursors asynchronously through atomic for the > >>> drm/rockchip driver plus the DRM_CAP_ASYNC_UPDATE patch. > >>> > >>> Alexandros also did a proof-of-concept to use this flag and draw cursors > >>> using atomic if possible on ozone [1]. > >>> > >>> Thanks > >>> Helen > >>> > >>> [1] https://chromium-review.googlesource.com/c/chromium/src/+/1092711 > >>> [2] https://gitlab.collabora.com/eballetbo/drm-cursor/commits/async-capability > >>> > >>> > >>> Changes in v2: > >>> - rebase tree > >>> - do not fall back to a non-async update if if there isn't any > >>> pending commit to amend > >>> > >>> Changes in v1: > >>> - https://patchwork.freedesktop.org/patch/243088/ > >>> - Only enable it if userspace requests it. > >>> - Only allow async update for cursor type planes. > >>> - Rename ASYNC_UPDATE for ATOMIC_AMEND. > >>> > >>> drivers/gpu/drm/drm_atomic_helper.c | 6 +++++- > >>> drivers/gpu/drm/drm_atomic_uapi.c | 6 ++++++ > >>> include/uapi/drm/drm_mode.h | 4 +++- > >>> 3 files changed, 14 insertions(+), 2 deletions(-) > >>> > >>> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > >>> index 269f1a74de38..333190c6a0a4 100644 > >>> --- a/drivers/gpu/drm/drm_atomic_helper.c > >>> +++ b/drivers/gpu/drm/drm_atomic_helper.c > >>> @@ -934,7 +934,7 @@ int drm_atomic_helper_check(struct drm_device *dev, > >>> if (ret) > >>> return ret; > >>> > >>> - if (state->legacy_cursor_update) > >>> + if (state->async_update || state->legacy_cursor_update) > >>> state->async_update = !drm_atomic_helper_async_check(dev, state); > > I just realized this is wrong, drm_atomic_helper_async_check() should > return error if there is a pending old_plane_state->commit (this v2 > patch is not doing this, but v1 was), if drm_atomic_helper_async_check() > returned because of it, then we should return error here to scale this > failure to userspace. Make sense? Tomasz, do you agree? > > >>> > >>> return ret; > >>> @@ -1602,6 +1602,10 @@ int drm_atomic_helper_async_check(struct drm_device *dev, > >>> if (new_plane_state->fence) > >>> return -EINVAL; > >>> > >>> + /* Only allow async update for cursor type planes. */ > >>> + if (plane->type != DRM_PLANE_TYPE_CURSOR) > >>> + return -EINVAL; > >>> + > >> > >> So the existing upstream code already allowed this for any planes and > >> we're restricting this to cursor planes only. Is this expected? No > >> potential users that already started using this for other plane types? > > > > The backend supports it for anything right now (if the driver implements > > it, that is). We do expose it through the legacy cursor api, and the > > legacy page_flip api, but not through atomic itself. It also has the > > problem that the not all drivers who support the async legacy cursor mode > > in atomic use this new infrastructure, so there's a few problems. Plus > > semantics are very ill-defined (we'd definitely need igt testcases for > > this stuff, especially all the new combinations with events, fences, ...). > > > > I think what we'd need here to make sure we're not digging an uapi hole: > > > > 1. Entirely remove the legacy_cursor_update hack. There's some patches > > floating around, but would need to be polished. > > > > 2. Make sure all drivers supporting legacy async cursor updates do through > > the async_plane update infrastructure. > > > > 3. Get the async plane update stuff merged for amdgpu. Iirc that's still > > stuck somewhere (but I'm not 100% sure what exactly they're doing). > > > > 4. Pile of igt testcases for all the new corner cases exposing this in > > atomic opens up. Many cases we might want to simply reject it. > > > > 5. Userspace. Big one I have is whether we need a flag like ALLOW_MODESET, > > since the current code transparently falls back to vblank-synced updates > > if async updates aren't available. > > > > tldr; lots of work. Also maybe: > > > > 0. Dump this todo into Documentation/gpu/todo.rst so it won't get lost. > > > > Cheers, Daniel > > > > Thanks Daniel for pointing those out, I'll start to take a look on them. > > > > >> > >> Best regards, > >> Tomasz > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@lists.freedesktop.org > >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > > Thanks > Helen > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch