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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 D4302C433B4 for ; Thu, 20 May 2021 16:29:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B15D860FD9 for ; Thu, 20 May 2021 16:29:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231980AbhETQau (ORCPT ); Thu, 20 May 2021 12:30:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54924 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233899AbhETQat (ORCPT ); Thu, 20 May 2021 12:30:49 -0400 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3FC7FC06175F for ; Thu, 20 May 2021 09:29:27 -0700 (PDT) Received: by mail-wr1-x42a.google.com with SMTP id i17so18281015wrq.11 for ; Thu, 20 May 2021 09:29:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to; bh=7gQAHjRkLz/zMdR9mZ20XGXZokHUiVVILLkWbVKY8vk=; b=cfxPfL5fE4np3aef6bq9mbEbsf+V7xoFH7lEgZwO4Pdk/oIevk19Q3UyCSV9vCBR57 oqDSJZrYGS54dgw1cyxBLzrZ9nUvG4J7evXugn3/Hrkt2MbKDwd4terqRk3pzf997Vak U6KAj9L1Il+SoamKwZJ4AlfDNCbUAwVjuKR+8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to; bh=7gQAHjRkLz/zMdR9mZ20XGXZokHUiVVILLkWbVKY8vk=; b=EAtIFACVujOXYF8njtb/3E0JrpViPvY19bqCxAaCSueqkY9+4ley/K4fOntad+aNZ0 s0WeZqWN/WAkaq39hxESrPun77dKwcEJo8WmTx4VpIy59m6H6vMpLmnIcncKZFnpMWtD iII8bbK5Xw/UAdq2AC/8YpVIOXMz5HLCwz/X9GYfGnoYZ9YEL6E0HAJcnOWgpMCTakEu 9omw6OlrMYAk5I8Yf9DSqNPPIdFvQ01+foywfuuUMtEmx2TGNBFP7dN6XuPDlo1yAafN q2Wv5elpjoKEZu5jv+rx1bx7VttGXCvX3hwwP5kLj6Gl0sBgNgR2yFplYcGXdynCoX6z jEbQ== X-Gm-Message-State: AOAM531kXwLMR2jJMynetqf0dA+LGCdjRspT5f9U6jzI2k5VgsDI/AOW a0T1t7YfEcSXNuWXcx+Slg3SvE+3UMbWbA== X-Google-Smtp-Source: ABdhPJx7W+fNXWLlfVnpy0Ca20BF42f6arhZCvq55cuTsYgbnk9UslMHeFLkM6bUwg6sp/BGFgOCqQ== X-Received: by 2002:a5d:6683:: with SMTP id l3mr5097252wru.398.1621528165809; Thu, 20 May 2021 09:29:25 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id g4sm3156003wmk.45.2021.05.20.09.29.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 May 2021 09:29:25 -0700 (PDT) Date: Thu, 20 May 2021 18:29:23 +0200 From: Daniel Vetter To: Rob Clark Cc: dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Rob Clark , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , open list , Matthew Brost Subject: Re: [RFC 2/3] drm/atomic: Call dma_fence_boost() when we've missed a vblank Message-ID: Mail-Followup-To: Rob Clark , dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Rob Clark , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , open list , Matthew Brost References: <20210519183855.1523927-1-robdclark@gmail.com> <20210519183855.1523927-3-robdclark@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210519183855.1523927-3-robdclark@gmail.com> X-Operating-System: Linux phenom 5.10.32scarlett+ Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Wed, May 19, 2021 at 11:38:53AM -0700, Rob Clark wrote: > From: Rob Clark > > Signed-off-by: Rob Clark > --- > drivers/gpu/drm/drm_atomic_helper.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > index 560aaecba31b..fe10fc2e7f86 100644 > --- a/drivers/gpu/drm/drm_atomic_helper.c > +++ b/drivers/gpu/drm/drm_atomic_helper.c > @@ -1435,11 +1435,15 @@ int drm_atomic_helper_wait_for_fences(struct drm_device *dev, > int i, ret; > > for_each_new_plane_in_state(state, plane, new_plane_state, i) { > + u64 vblank_count; > + > if (!new_plane_state->fence) > continue; > > WARN_ON(!new_plane_state->fb); > > + vblank_count = drm_crtc_vblank_count(new_plane_state->crtc); > + > /* > * If waiting for fences pre-swap (ie: nonblock), userspace can > * still interrupt the operation. Instead of blocking until the > @@ -1449,6 +1453,13 @@ int drm_atomic_helper_wait_for_fences(struct drm_device *dev, > if (ret) > return ret; > > + /* > + * Check if we've missed a vblank while waiting, and if we have > + * signal the fence that it's signaler should be boosted > + */ > + if (vblank_count != drm_crtc_vblank_count(new_plane_state->crtc)) > + dma_fence_boost(new_plane_state->fence); I think we should do a lot better here: - maybe only bother doing this for single-crtc updates, and only if modeset isn't set. No one else cares about latency. - We should boost _right_ when we've missed the frame, so I think we should have a _timeout wait here that guesstimates when the vblank is over (might need to throw in a vblank wait if we missed) and then boost immediately. Not wait a bunch of frames (worst case) until we finally decide to boost. Otherwise I really like this, I think it's about the only real reason i915 isn't using atomic helpers. Also adding Matt B for this topic. -Daniel > + > dma_fence_put(new_plane_state->fence); > new_plane_state->fence = NULL; > } > -- > 2.30.2 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch