From patchwork Tue Feb 9 10:15:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12077665 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 C75D6C433E6 for ; Tue, 9 Feb 2021 10:15:34 +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 006B564E77 for ; Tue, 9 Feb 2021 10:15:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 006B564E77 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch 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 92CA86EAC1; Tue, 9 Feb 2021 10:15:32 +0000 (UTC) Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by gabe.freedesktop.org (Postfix) with ESMTPS id 377C76EAC1 for ; Tue, 9 Feb 2021 10:15:31 +0000 (UTC) Received: by mail-wm1-x335.google.com with SMTP id i9so2907897wmq.1 for ; Tue, 09 Feb 2021 02:15:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+t2qfqYwBPduaMFSL0mQ9g24Z3UBoLu9uILpa+jiK5I=; b=kONOr12btORYEC/KZvwreyl9qPMWdrBc1WgjTbx613+RXItRRH7rJe/iD6YUR6guxQ lxV+6p+v+MjJZZD5zMjfS8e1IJVLi8eDHlE7u7nT9UO8ns3UeklMTOBPaehrplvUXY7X 7mAnUS0y/TKy2czupGMtN6gMxZeTnc8SzAMwk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+t2qfqYwBPduaMFSL0mQ9g24Z3UBoLu9uILpa+jiK5I=; b=Ag2M8wYQBIWnCPjuUh8UTzKoldLN859jdZqXAy9DK/zZVRbVR8snqhjVi4bUB1xpin /Wz8HwfFdefZQzlAINr9UPsJe4OlYliqc13WtILlmX+lqCWKLESfOyB0sQ7W5Vfg7HFR Gj3tJ4yojln0klFskuPd2vOrYrW1u2KGVB03EZtpXE3e3Y6pkbr44tYfb3A+Tuuah1+a 6fgQJf0zWFaipuw7/ruE9eRRffZXdCpcAQTTR3ZZkZza5vpKEA1k/grcf5lJLIFv+yWI uRy5/Q/iMtQOmUY+KOwoA8VFxDjhuK4gqxt4V0g5btYFNMiqFrVuiW5wTaSfHEGZpncv nKDw== X-Gm-Message-State: AOAM5304PVYoKSsZeUKDHYy9ImqyUfSKgBTm7IbdOATCqzX3tnYYWEBZ jYOnKmT2n+JQ5FQG0Pb+1wcjw3ashc8LypIe X-Google-Smtp-Source: ABdhPJwtXdgun71HKK/LPw0y2lZP1i4QNMgEJ/nr6c4XyYeuuSOsKuCq3K6ergANYCRsVMJuPqHq5Q== X-Received: by 2002:a7b:c04c:: with SMTP id u12mr2746466wmc.185.1612865729738; Tue, 09 Feb 2021 02:15:29 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id j39sm9530484wrj.21.2021.02.09.02.15.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Feb 2021 02:15:29 -0800 (PST) From: Daniel Vetter To: DRI Development Subject: [PATCH] drm/vblank: Document drm_crtc_vblank_restore constraints Date: Tue, 9 Feb 2021 11:15:23 +0100 Message-Id: <20210209101523.2954281-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.30.0 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: Daniel Vetter , Intel Graphics Development , Daniel Vetter Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" I got real badly confused when trying to review a fix from Ville for this. Let's try to document better what's required for this, and check the minimal settings at runtime - we can't check ofc that there's indeed no races in the driver callback. Also noticed that the drm_vblank_restore version is unused, so lets unexport that while at it. Cc: Ville Syrjala Signed-off-by: Daniel Vetter Reviewed-by: Ville Syrjälä --- drivers/gpu/drm/drm_vblank.c | 25 ++++++++++--------------- include/drm/drm_vblank.h | 1 - 2 files changed, 10 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index c914b14cfb43..05f4d4c078fd 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -1471,20 +1471,7 @@ void drm_crtc_vblank_on(struct drm_crtc *crtc) } EXPORT_SYMBOL(drm_crtc_vblank_on); -/** - * drm_vblank_restore - estimate missed vblanks and update vblank count. - * @dev: DRM device - * @pipe: CRTC index - * - * Power manamement features can cause frame counter resets between vblank - * disable and enable. Drivers can use this function in their - * &drm_crtc_funcs.enable_vblank implementation to estimate missed vblanks since - * the last &drm_crtc_funcs.disable_vblank using timestamps and update the - * vblank counter. - * - * This function is the legacy version of drm_crtc_vblank_restore(). - */ -void drm_vblank_restore(struct drm_device *dev, unsigned int pipe) +static void drm_vblank_restore(struct drm_device *dev, unsigned int pipe) { ktime_t t_vblank; struct drm_vblank_crtc *vblank; @@ -1520,7 +1507,6 @@ void drm_vblank_restore(struct drm_device *dev, unsigned int pipe) diff, diff_ns, framedur_ns, cur_vblank - vblank->last); store_vblank(dev, pipe, diff, t_vblank, cur_vblank); } -EXPORT_SYMBOL(drm_vblank_restore); /** * drm_crtc_vblank_restore - estimate missed vblanks and update vblank count. @@ -1531,9 +1517,18 @@ EXPORT_SYMBOL(drm_vblank_restore); * &drm_crtc_funcs.enable_vblank implementation to estimate missed vblanks since * the last &drm_crtc_funcs.disable_vblank using timestamps and update the * vblank counter. + * + * Note that drivers must have race-free high-precision timestamping support, + * i.e. &drm_crtc_funcs.get_vblank_timestamp must be hooked up and + * &drm_driver.vblank_disable_immediate must be set to indicate the + * time-stamping functions are race-free against vblank hardware counter + * increments. */ void drm_crtc_vblank_restore(struct drm_crtc *crtc) { + WARN_ON_ONCE(!crtc->funcs->get_vblank_timestamp); + WARN_ON_ONCE(!crtc->dev->vblank_disable_immediate); + drm_vblank_restore(crtc->dev, drm_crtc_index(crtc)); } EXPORT_SYMBOL(drm_crtc_vblank_restore); diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h index dd125f8c766c..733a3e2d1d10 100644 --- a/include/drm/drm_vblank.h +++ b/include/drm/drm_vblank.h @@ -247,7 +247,6 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc); void drm_crtc_vblank_reset(struct drm_crtc *crtc); void drm_crtc_vblank_on(struct drm_crtc *crtc); u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc); -void drm_vblank_restore(struct drm_device *dev, unsigned int pipe); void drm_crtc_vblank_restore(struct drm_crtc *crtc); void drm_calc_timestamping_constants(struct drm_crtc *crtc,