From patchwork Fri Oct 30 07:08:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Boris Brezillon X-Patchwork-Id: 11868609 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=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 96782C4742C for ; Fri, 30 Oct 2020 07:08:36 +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 08AFB22228 for ; Fri, 30 Oct 2020 07:08:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 08AFB22228 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 947346E02C; Fri, 30 Oct 2020 07:08:34 +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 406B36E02C for ; Fri, 30 Oct 2020 07:08:33 +0000 (UTC) Received: from localhost.localdomain (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id C99901F45955; Fri, 30 Oct 2020 07:08:31 +0000 (GMT) From: Boris Brezillon To: Rob Herring , Tomeu Vizoso , Alyssa Rosenzweig , Steven Price , Robin Murphy Subject: [PATCH] drm/panfrost: Move the GPU reset bits outside the timeout handler Date: Fri, 30 Oct 2020 08:08:26 +0100 Message-Id: <20201030070826.582969-1-boris.brezillon@collabora.com> X-Mailer: git-send-email 2.26.2 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: Boris Brezillon , stable@vger.kernel.org, dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" We've fixed many races in panfrost_job_timedout() but some remain. Instead of trying to fix it again, let's simplify the logic and move the reset bits to a separate work scheduled when one of the queue reports a timeout. Fixes: 1a11a88cfd9a ("drm/panfrost: Fix job timeout handling") Cc: Signed-off-by: Boris Brezillon --- drivers/gpu/drm/panfrost/panfrost_device.c | 1 - drivers/gpu/drm/panfrost/panfrost_device.h | 6 +- drivers/gpu/drm/panfrost/panfrost_job.c | 130 ++++++++++++--------- 3 files changed, 82 insertions(+), 55 deletions(-) diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c index ea8d31863c50..a83b2ff5837a 100644 --- a/drivers/gpu/drm/panfrost/panfrost_device.c +++ b/drivers/gpu/drm/panfrost/panfrost_device.c @@ -200,7 +200,6 @@ int panfrost_device_init(struct panfrost_device *pfdev) struct resource *res; mutex_init(&pfdev->sched_lock); - mutex_init(&pfdev->reset_lock); INIT_LIST_HEAD(&pfdev->scheduled_jobs); INIT_LIST_HEAD(&pfdev->as_lru_list); diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h index 2e9cbd1c4a58..67f9f66904be 100644 --- a/drivers/gpu/drm/panfrost/panfrost_device.h +++ b/drivers/gpu/drm/panfrost/panfrost_device.h @@ -105,7 +105,11 @@ struct panfrost_device { struct panfrost_perfcnt *perfcnt; struct mutex sched_lock; - struct mutex reset_lock; + + struct { + struct work_struct work; + atomic_t pending; + } reset; struct mutex shrinker_lock; struct list_head shrinker_list; diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c index d0469e944143..745ee9563a54 100644 --- a/drivers/gpu/drm/panfrost/panfrost_job.c +++ b/drivers/gpu/drm/panfrost/panfrost_job.c @@ -20,6 +20,8 @@ #include "panfrost_gpu.h" #include "panfrost_mmu.h" +#define JOB_TIMEOUT_MS 500 + #define job_write(dev, reg, data) writel(data, dev->iomem + (reg)) #define job_read(dev, reg) readl(dev->iomem + (reg)) @@ -382,19 +384,37 @@ static bool panfrost_scheduler_stop(struct panfrost_queue_state *queue, drm_sched_increase_karma(bad); queue->stopped = true; stopped = true; + + /* + * Set the timeout to max so the timer doesn't get started + * when we return from the timeout handler (restored in + * panfrost_scheduler_start()). + */ + queue->sched.timeout = MAX_SCHEDULE_TIMEOUT; } mutex_unlock(&queue->lock); return stopped; } +static void panfrost_scheduler_start(struct panfrost_queue_state *queue) +{ + if (WARN_ON(!queue->stopped)) + return; + + mutex_lock(&queue->lock); + /* Restore the original timeout before starting the scheduler. */ + queue->sched.timeout = msecs_to_jiffies(JOB_TIMEOUT_MS); + drm_sched_start(&queue->sched, true); + queue->stopped = false; + mutex_unlock(&queue->lock); +} + static void panfrost_job_timedout(struct drm_sched_job *sched_job) { struct panfrost_job *job = to_panfrost_job(sched_job); struct panfrost_device *pfdev = job->pfdev; int js = panfrost_job_get_slot(job); - unsigned long flags; - int i; /* * If the GPU managed to complete this jobs fence, the timeout is @@ -415,56 +435,9 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job) if (!panfrost_scheduler_stop(&pfdev->js->queue[js], sched_job)) return; - if (!mutex_trylock(&pfdev->reset_lock)) - return; - - for (i = 0; i < NUM_JOB_SLOTS; i++) { - struct drm_gpu_scheduler *sched = &pfdev->js->queue[i].sched; - - /* - * If the queue is still active, make sure we wait for any - * pending timeouts. - */ - if (!pfdev->js->queue[i].stopped) - cancel_delayed_work_sync(&sched->work_tdr); - - /* - * If the scheduler was not already stopped, there's a tiny - * chance a timeout has expired just before we stopped it, and - * drm_sched_stop() does not flush pending works. Let's flush - * them now so the timeout handler doesn't get called in the - * middle of a reset. - */ - if (panfrost_scheduler_stop(&pfdev->js->queue[i], NULL)) - cancel_delayed_work_sync(&sched->work_tdr); - - /* - * Now that we cancelled the pending timeouts, we can safely - * reset the stopped state. - */ - pfdev->js->queue[i].stopped = false; - } - - spin_lock_irqsave(&pfdev->js->job_lock, flags); - for (i = 0; i < NUM_JOB_SLOTS; i++) { - if (pfdev->jobs[i]) { - pm_runtime_put_noidle(pfdev->dev); - panfrost_devfreq_record_idle(&pfdev->pfdevfreq); - pfdev->jobs[i] = NULL; - } - } - spin_unlock_irqrestore(&pfdev->js->job_lock, flags); - - panfrost_device_reset(pfdev); - - for (i = 0; i < NUM_JOB_SLOTS; i++) - drm_sched_resubmit_jobs(&pfdev->js->queue[i].sched); - - mutex_unlock(&pfdev->reset_lock); - - /* restart scheduler after GPU is usable again */ - for (i = 0; i < NUM_JOB_SLOTS; i++) - drm_sched_start(&pfdev->js->queue[i].sched, true); + /* Schedule a reset. */ + atomic_set(&pfdev->reset.pending, 1); + schedule_work(&pfdev->reset.work); } static const struct drm_sched_backend_ops panfrost_sched_ops = { @@ -531,11 +504,62 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void *data) return IRQ_HANDLED; } +static void panfrost_reset(struct work_struct *work) +{ + struct panfrost_device *pfdev = container_of(work, + struct panfrost_device, + reset.work); + unsigned long flags; + unsigned int i; + + if (!atomic_read(&pfdev->reset.pending)) + return; + + for (i = 0; i < NUM_JOB_SLOTS; i++) { + /* + * We want pending timeouts to be handled before we attempt + * to stop the scheduler. If we don't do that and the timeout + * handler is in flight, it might have removed the bad job + * from the list, and we'll lose this job if the reset handler + * enters the critical section in panfrost_scheduler_stop() + * before the timeout handler. + * + * Timeout is set to max to make sure the timer is not + * restarted after the cancellation. + */ + pfdev->js->queue[i].sched.timeout = MAX_SCHEDULE_TIMEOUT; + cancel_delayed_work_sync(&pfdev->js->queue[i].sched.work_tdr); + panfrost_scheduler_stop(&pfdev->js->queue[i], NULL); + } + + /* All timers have been stopped, we can safely reset the pending state. */ + atomic_set(&pfdev->reset.pending, 0); + + spin_lock_irqsave(&pfdev->js->job_lock, flags); + for (i = 0; i < NUM_JOB_SLOTS; i++) { + if (pfdev->jobs[i]) { + pm_runtime_put_noidle(pfdev->dev); + panfrost_devfreq_record_idle(&pfdev->pfdevfreq); + pfdev->jobs[i] = NULL; + } + } + spin_unlock_irqrestore(&pfdev->js->job_lock, flags); + + panfrost_device_reset(pfdev); + + for (i = 0; i < NUM_JOB_SLOTS; i++) { + drm_sched_resubmit_jobs(&pfdev->js->queue[i].sched); + panfrost_scheduler_start(&pfdev->js->queue[i]); + } +} + int panfrost_job_init(struct panfrost_device *pfdev) { struct panfrost_job_slot *js; int ret, j, irq; + INIT_WORK(&pfdev->reset.work, panfrost_reset); + pfdev->js = js = devm_kzalloc(pfdev->dev, sizeof(*js), GFP_KERNEL); if (!js) return -ENOMEM; @@ -558,7 +582,7 @@ int panfrost_job_init(struct panfrost_device *pfdev) ret = drm_sched_init(&js->queue[j].sched, &panfrost_sched_ops, - 1, 0, msecs_to_jiffies(500), + 1, 0, msecs_to_jiffies(JOB_TIMEOUT_MS), "pan_js"); if (ret) { dev_err(pfdev->dev, "Failed to create scheduler: %d.", ret);