From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2243538-1518720699-2-13492618655647038151 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1518720698; b=EOjJAFU6O6Cx2VuNBjZSuLnVAa5qzlKG5XYCAOWn4wTalpJ 3hYYTjjbGgtJrWgi4qVCQGWwqzz2zfrBTNc5AYJPhD2nrqJ7U562c8oMPrhFyH5g qa7msnMipSx2U4nB2ukGwL1JmTwFHkjp0WUOOl67ui65VnqebB5aplbSHz9pysA+ BnTumzDZmUq/BLHcvYs2IbMkeEM8VFW7isTRfD6szm5MvkJ8RMeMFsY07irFEvXf iVRLRYAxZDDLLNEIDZ/hZK6pnQk3o5jgLOGQEzyz1CZgr4KZWNNNyvMtRaJzrR+A Isi3fCPDCOFGIoMFLvsn438z+Bf76+IrDc/WWcg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1518720698; bh=aZzyfSVy2MTJWMiOwA9qPlojGH +G61KIybC9lRN4PwE=; b=T7yAp0hKvngdDe8my4NA1pIxuzvdJ9iYrU9la4s0cq q9sw2hsNQa8IiyEQQ+vcWjJYQDeyMVU809vOUfeK18aU3dRSueHr4LyPTYmv2mLH 7Qu01uDnFzGYbvkhLntwoCWxgHN3yC+76TygPB2F68GQKWSfcSw+Hb1FXuGyeTS4 2Ls9tn9Qe+QICEKZ8ifv9zvEMCbfsbq2q+5d4kN8p3Yrji4OOZM+JgplakOzQf/0 1xo6YC7v8j2dTKAokP48yU40uRRSXxXODjnnbfFEJ/qevcAYFyq9niFUOFx6wuu+ 9VlUhJLrXN4m6D8PwYTepFBDCVF/a/p3cnfXHbHKXAVQ== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162217AbeBOSvW (ORCPT ); Thu, 15 Feb 2018 13:51:22 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:48982 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162064AbeBOPV2 (ORCPT ); Thu, 15 Feb 2018 10:21:28 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Laurent Pinchart , Kieran Bingham , thongsyho , Nhan Nguyen Subject: [PATCH 4.4 025/108] drm: rcar-du: Fix race condition when disabling planes at CRTC stop Date: Thu, 15 Feb 2018 16:16:22 +0100 Message-Id: <20180215151226.076346687@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180215151222.267507937@linuxfoundation.org> References: <20180215151222.267507937@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Laurent Pinchart commit 641307df71fe77d7b38a477067495ede05d47295 upstream. When stopping the CRTC the driver must disable all planes and wait for the change to take effect at the next vblank. Merely calling drm_crtc_wait_one_vblank() is not enough, as the function doesn't include any mechanism to handle the race with vblank interrupts. Replace the drm_crtc_wait_one_vblank() call with a manual mechanism that handles the vblank interrupt race. Signed-off-by: Laurent Pinchart Reviewed-by: Kieran Bingham Signed-off-by: thongsyho Signed-off-by: Nhan Nguyen Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 54 +++++++++++++++++++++++++++++---- drivers/gpu/drm/rcar-du/rcar_du_crtc.h | 8 ++++ 2 files changed, 56 insertions(+), 6 deletions(-) --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c @@ -371,6 +371,31 @@ static void rcar_du_crtc_start(struct rc rcrtc->started = true; } +static void rcar_du_crtc_disable_planes(struct rcar_du_crtc *rcrtc) +{ + struct rcar_du_device *rcdu = rcrtc->group->dev; + struct drm_crtc *crtc = &rcrtc->crtc; + u32 status; + /* Make sure vblank interrupts are enabled. */ + drm_crtc_vblank_get(crtc); + /* + * Disable planes and calculate how many vertical blanking interrupts we + * have to wait for. If a vertical blanking interrupt has been triggered + * but not processed yet, we don't know whether it occurred before or + * after the planes got disabled. We thus have to wait for two vblank + * interrupts in that case. + */ + spin_lock_irq(&rcrtc->vblank_lock); + rcar_du_group_write(rcrtc->group, rcrtc->index % 2 ? DS2PR : DS1PR, 0); + status = rcar_du_crtc_read(rcrtc, DSSR); + rcrtc->vblank_count = status & DSSR_VBK ? 2 : 1; + spin_unlock_irq(&rcrtc->vblank_lock); + if (!wait_event_timeout(rcrtc->vblank_wait, rcrtc->vblank_count == 0, + msecs_to_jiffies(100))) + dev_warn(rcdu->dev, "vertical blanking timeout\n"); + drm_crtc_vblank_put(crtc); +} + static void rcar_du_crtc_stop(struct rcar_du_crtc *rcrtc) { struct drm_crtc *crtc = &rcrtc->crtc; @@ -379,17 +404,16 @@ static void rcar_du_crtc_stop(struct rca return; /* Disable all planes and wait for the change to take effect. This is - * required as the DSnPR registers are updated on vblank, and no vblank - * will occur once the CRTC is stopped. Disabling planes when starting - * the CRTC thus wouldn't be enough as it would start scanning out - * immediately from old frame buffers until the next vblank. + * required as the plane enable registers are updated on vblank, and no + * vblank will occur once the CRTC is stopped. Disabling planes when + * starting the CRTC thus wouldn't be enough as it would start scanning + * out immediately from old frame buffers until the next vblank. * * This increases the CRTC stop delay, especially when multiple CRTCs * are stopped in one operation as we now wait for one vblank per CRTC. * Whether this can be improved needs to be researched. */ - rcar_du_group_write(rcrtc->group, rcrtc->index % 2 ? DS2PR : DS1PR, 0); - drm_crtc_wait_one_vblank(crtc); + rcar_du_crtc_disable_planes(rcrtc); /* Disable vertical blanking interrupt reporting. We first need to wait * for page flip completion before stopping the CRTC as userspace @@ -528,10 +552,26 @@ static irqreturn_t rcar_du_crtc_irq(int irqreturn_t ret = IRQ_NONE; u32 status; + spin_lock(&rcrtc->vblank_lock); + status = rcar_du_crtc_read(rcrtc, DSSR); rcar_du_crtc_write(rcrtc, DSRCR, status & DSRCR_MASK); if (status & DSSR_VBK) { + /* + * Wake up the vblank wait if the counter reaches 0. This must + * be protected by the vblank_lock to avoid races in + * rcar_du_crtc_disable_planes(). + */ + if (rcrtc->vblank_count) { + if (--rcrtc->vblank_count == 0) + wake_up(&rcrtc->vblank_wait); + } + } + + spin_unlock(&rcrtc->vblank_lock); + + if (status & DSSR_VBK) { drm_handle_vblank(rcrtc->crtc.dev, rcrtc->index); rcar_du_crtc_finish_page_flip(rcrtc); ret = IRQ_HANDLED; @@ -585,6 +625,8 @@ int rcar_du_crtc_create(struct rcar_du_g } init_waitqueue_head(&rcrtc->flip_wait); + init_waitqueue_head(&rcrtc->vblank_wait); + spin_lock_init(&rcrtc->vblank_lock); rcrtc->group = rgrp; rcrtc->mmio_offset = mmio_offsets[index]; --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h @@ -15,6 +15,7 @@ #define __RCAR_DU_CRTC_H__ #include +#include #include #include @@ -32,6 +33,9 @@ struct rcar_du_group; * @started: whether the CRTC has been started and is running * @event: event to post when the pending page flip completes * @flip_wait: wait queue used to signal page flip completion + * @vblank_lock: protects vblank_wait and vblank_count + * @vblank_wait: wait queue used to signal vertical blanking + * @vblank_count: number of vertical blanking interrupts to wait for * @outputs: bitmask of the outputs (enum rcar_du_output) driven by this CRTC * @enabled: whether the CRTC is enabled, used to control system resume * @group: CRTC group this CRTC belongs to @@ -48,6 +52,10 @@ struct rcar_du_crtc { struct drm_pending_vblank_event *event; wait_queue_head_t flip_wait; + spinlock_t vblank_lock; + wait_queue_head_t vblank_wait; + unsigned int vblank_count; + unsigned int outputs; bool enabled;