From patchwork Wed Mar 8 16:43:19 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robert Jarzmik X-Patchwork-Id: 9611647 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 9244D60414 for ; Wed, 8 Mar 2017 16:43:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9B82C28622 for ; Wed, 8 Mar 2017 16:43:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9060928626; Wed, 8 Mar 2017 16:43:30 +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,FREEMAIL_FROM, 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 7792828622 for ; Wed, 8 Mar 2017 16:43:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753893AbdCHQn1 (ORCPT ); Wed, 8 Mar 2017 11:43:27 -0500 Received: from smtp04.smtpout.orange.fr ([80.12.242.126]:24603 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752620AbdCHQnZ (ORCPT ); Wed, 8 Mar 2017 11:43:25 -0500 Received: from belgarion ([92.149.59.52]) by mwinf5d07 with ME id tUjL1u00517d2Es03UjLfd; Wed, 08 Mar 2017 17:43:22 +0100 X-ME-Helo: belgarion X-ME-Auth: amFyem1pay5yb2JlcnRAb3JhbmdlLmZy X-ME-Date: Wed, 08 Mar 2017 17:43:22 +0100 X-ME-IP: 92.149.59.52 From: Robert Jarzmik To: Petr Cvek Cc: vinod.koul@intel.com, Ulf Hansson , Daniel Mack , Haojian Zhuang , linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dmaengine@vger.kernel.org Subject: Re: [BUG] dmaengine: pxa_dma: + mmc: pxamci: race condition with DMA error on tx channel References: X-URL: http://belgarath.falguerolles.org/ Date: Wed, 08 Mar 2017 17:43:19 +0100 In-Reply-To: (Petr Cvek's message of "Wed, 8 Mar 2017 07:57:08 +0100") Message-ID: <877f3zwwgo.fsf@belgarion.home> User-Agent: Gnus/5.130008 (Ma Gnus v0.8) Emacs/24.4 (gnu/linux) MIME-Version: 1.0 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Petr Cvek writes: Hi Petr, > I wasn't able to track the problem to a single patch as the problem occurs at > random time (from the boot to like a half an hour) and it's maybe dependent on a > level of a battery charge (maybe because of kernel log writes of charging > messages). Mmmh, long reproduction time, that will be bad. > It seems that most occurrency is during writes on an SD card. Using an SDHC > card decreases the time to fail. After failure the OS is unavailable (rootfs > in on the card). Okay, let me try to make write loop on my SD card to see if I manage to reproduce this. > From my poking in the kernel source code it seems there is a probability that pxamci_irq() takes longer to call and its subsequent call pxamci_data_done() isn't fast enough to set [1] > host->data = NULL; > From the DMA side, the DMA done interrupt is generated: > pxad_chan_handler() -> vchan_cookie_complete() > ...where a tasklet for vchan_complete() is scheduled At least that seems to hint the DMA part is sound so for. The bothering part is the log error "mmc0: DMA error on tx channel". I would need a bit of guidance here, with the same log with [1] applied. > , where finally with interrupts enabled (can pxamci_irq() be called here?) the > callback pxamci_dma_irq() is called. When DMA completes, there is a tiny window, before pxamci_dma_irq() is called, when pxamci_irq() can be called, yes. As soon as the spinlock is taken in pxamci_dma_irq() is taken, no more races. > From my tests it seems at this point [2] the host->data is always NULL and rest > of the callback is never called. It is called once with a nonempty host->data > only just before the failure. > > During the testing I put udelay(100) at the start of pxamci_dma_irq() and fail > occurred after like 2 hours (when I for the first time tapped the touchscreen - > higher CPU usage and interrupts). Mmm I would need more data here. The biggest help I could get would be the pxa dma traces here : echo -n 'file pxa_dma.c +p' > /sys/kernel/debug/dynamic_debug/control echo -n 'file virt-dma.c +p' > /sys/kernel/debug/dynamic_debug/control And then capture the last traces and send them to me. Cheers. diff --git a/drivers/mmc/host/pxamci.c b/drivers/mmc/host/pxamci.c index c763b404510f..ed3812b2a34d 100644 --- a/drivers/mmc/host/pxamci.c +++ b/drivers/mmc/host/pxamci.c @@ -571,8 +571,9 @@ static void pxamci_dma_irq(void *param) if (likely(status == DMA_COMPLETE)) { writel(BUF_PART_FULL, host->base + MMC_PRTBUF); } else { - pr_err("%s: DMA error on %s channel\n", mmc_hostname(host->mmc), - host->data->flags & MMC_DATA_READ ? "rx" : "tx"); + pr_err("%s: DMA error on %s channel: %d\n", + mmc_hostname(host->mmc), + host->data->flags & MMC_DATA_READ ? "rx" : "tx", status); host->data->error = -EIO; pxamci_data_done(host, 0); }