From patchwork Thu Jan 12 17:09:00 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Lindgren X-Patchwork-Id: 9513651 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id DCCDA601E7 for ; Thu, 12 Jan 2017 17:10:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C8296286A5 for ; Thu, 12 Jan 2017 17:10:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BCCC5286F4; Thu, 12 Jan 2017 17:10:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 29688286A5 for ; Thu, 12 Jan 2017 17:10:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750733AbdALRJ6 (ORCPT ); Thu, 12 Jan 2017 12:09:58 -0500 Received: from muru.com ([72.249.23.125]:56618 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750914AbdALRJF (ORCPT ); Thu, 12 Jan 2017 12:09:05 -0500 Received: from atomide.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id E29E6827F; Thu, 12 Jan 2017 17:09:45 +0000 (UTC) Date: Thu, 12 Jan 2017 09:09:00 -0800 From: Tony Lindgren To: Alexandre Bailon Cc: vinod.koul@intel.com, dmaengine@vger.kernel.org, linux-usb@vger.kernel.org, nsekhar@ti.com, khilman@baylibre.com, ptitiano@baylibre.com, linux-omap@vger.kernel.org, andy.shevchenko@gmail.com Subject: Re: [PATCH v2 1/2] dmaengine: cppi41: Fix list not empty warning on runtime suspend Message-ID: <20170112170900.GG2630@atomide.com> References: <20170109170337.6957-1-abailon@baylibre.com> <20170109170337.6957-2-abailon@baylibre.com> <20170109183416.GJ2630@atomide.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20170109183416.GJ2630@atomide.com> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP * Tony Lindgren [170109 10:35]: > Hi, > > * Alexandre Bailon [170109 09:04]: > > Sometime, a transfer may not be queued due to a race between runtime pm > > and cppi41_dma_issue_pending(). > > Sometime, cppi41_runtime_resume() may be interrupted right before to > > update device PM state to RESUMED. > > When it happens, if a new dma transfer is issued, because the device is not > > in active state, the descriptor will be added to the pendding list. > > But because the descriptors in the pendding list are only queued to cppi41 > > on runtime resume, the descriptor will not be queued. > > On runtime suspend, the list is not empty, which is causing a warning. > > Queue the descriptor if the device is active or resuming. > > > > Signed-off-by: Alexandre Bailon > > --- > > drivers/dma/cppi41.c | 18 +++++++++++++++++- > > 1 file changed, 17 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c > > index d5ba43a..025fee4 100644 > > --- a/drivers/dma/cppi41.c > > +++ b/drivers/dma/cppi41.c > > @@ -471,6 +471,8 @@ static void cppi41_dma_issue_pending(struct dma_chan *chan) > > { > > struct cppi41_channel *c = to_cpp41_chan(chan); > > struct cppi41_dd *cdd = c->cdd; > > + unsigned long flags; > > + bool active; > > int error; > > > > error = pm_runtime_get(cdd->ddev.dev); > > @@ -482,7 +484,21 @@ static void cppi41_dma_issue_pending(struct dma_chan *chan) > > return; > > } > > > > - if (likely(pm_runtime_active(cdd->ddev.dev))) > > + active = pm_runtime_active(cdd->ddev.dev); > > + if (!active) { > > + /* > > + * Runtime resume may be interrupted before runtime_status > > + * has been updated. Test if device has resumed. > > + */ > > + if (error == -EINPROGRESS) { > > + spin_lock_irqsave(&cdd->lock, flags); > > + if (list_empty(&cdd->pending)) > > + active = true; > > + spin_unlock_irqrestore(&cdd->lock, flags); > > + } > > + } > > + > > + if (likely(active)) > > push_desc_queue(c); > > else > > pending_desc(c); > > What guarantees that the PM runtime state is really active few lines later? > > A safer approach might be to check the queue for new entries by in > cppi41_runtime_resume() using "while (!list_empty())" instead of > list_for_each_entry(). That releases the spinlock between each entry > and rechecks the list. > > And instead of doing WARN_ON(!list_empty(&cdd->pending)) it seems we > should run the queue also on cppi41_runtime_suspend()? Hmm so I started seeing these issues too with Linux next just plugging in USB cable on bbb while configured as a USB peripheral :) Below is what seems to fix issues for me, not seeing any more warnings either. Care to give it a try with your USB headset? Regards, Tony 8< -------------------------- --- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c --- a/drivers/dma/cppi41.c +++ b/drivers/dma/cppi41.c @@ -153,6 +153,8 @@ struct cppi41_dd { /* context for suspend/resume */ unsigned int dma_tdfdq; + + bool active; }; #define FIST_COMPLETION_QUEUE 93 @@ -320,7 +322,8 @@ static irqreturn_t cppi41_irq(int irq, void *data) int error; error = pm_runtime_get(cdd->ddev.dev); - if (error < 0) + if (((error != -EINPROGRESS) && error < 0) || + !cdd->active) dev_err(cdd->ddev.dev, "%s pm runtime get: %i\n", __func__, error); @@ -482,7 +485,7 @@ static void cppi41_dma_issue_pending(struct dma_chan *chan) return; } - if (likely(pm_runtime_active(cdd->ddev.dev))) + if (likely(cdd->active)) push_desc_queue(c); else pending_desc(c); @@ -1151,6 +1154,7 @@ static int __maybe_unused cppi41_runtime_suspend(struct device *dev) { struct cppi41_dd *cdd = dev_get_drvdata(dev); + cdd->active = false; WARN_ON(!list_empty(&cdd->pending)); return 0; @@ -1159,13 +1163,20 @@ static int __maybe_unused cppi41_runtime_suspend(struct device *dev) static int __maybe_unused cppi41_runtime_resume(struct device *dev) { struct cppi41_dd *cdd = dev_get_drvdata(dev); - struct cppi41_channel *c, *_c; + struct cppi41_channel *c; unsigned long flags; + cdd->active = true; + spin_lock_irqsave(&cdd->lock, flags); - list_for_each_entry_safe(c, _c, &cdd->pending, node) { - push_desc_queue(c); + while (!list_empty(&cdd->pending)) { + c = list_first_entry(&cdd->pending, + struct cppi41_channel, + node); list_del(&c->node); + spin_unlock_irqrestore(&cdd->lock, flags); + push_desc_queue(c); + spin_lock_irqsave(&cdd->lock, flags); } spin_unlock_irqrestore(&cdd->lock, flags);