From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932469AbcERQtM (ORCPT ); Wed, 18 May 2016 12:49:12 -0400 Received: from mga11.intel.com ([192.55.52.93]:57136 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752814AbcERQtL (ORCPT ); Wed, 18 May 2016 12:49:11 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.26,329,1459839600"; d="scan'208";a="979746202" From: "Jiang, Dave" To: "Koul, Vinod" , "gavin.guo@canonical.com" CC: "dmaengine@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Williams, Dan J" Subject: Re: ioatdma(Intel(R) I/OAT DMA Engine init failed) Thread-Topic: ioatdma(Intel(R) I/OAT DMA Engine init failed) Thread-Index: AQHRr1roHRN0U792LESGukoKn5IBYJ+9XlIAgAHKPoCAADhjAA== Date: Wed, 18 May 2016 16:49:08 +0000 Message-ID: <1463590132.5797.47.camel@intel.com> References: <20160517100656.GT23734@localhost> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [143.182.137.38] Content-Type: text/plain; charset="utf-8" Content-ID: <7B723B824A749B40828D4A35202C5F68@intel.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id u4IGnHt4029276 On Wed, 2016-05-18 at 13:27 +0000, Gavin Guo wrote: > On Tue, May 17, 2016 at 6:06 PM, Vinod Koul > wrote: > > > > On Mon, May 16, 2016 at 06:08:20PM +0800, Gavin Guo wrote: > > > > > > The following error messages can be observed on the Intel > > > Haswell-E > > > chipset with v3.13 kernel. After the analysis, I found there is > > > no > > > difference in the logic of these error messages in the current > > > upstream kernel. I also searched the git log and can't find any > > > commit > > > which is fix to the error(correct me if I am wrong). The > > > following is > > > the detail, and I'll really appreciate if there is any comment. > > > :) > > 3.13 is ancient, can you check this on latest kernel > Thank you for the comment. It's running on the production system. > However, > I'll try to figure out if it's possible to test the latest kernel. I wonder if you don't have the extended PCI config space access enabled in your kernel config.  > > > > > > > > > > > > > > ioatdma 0000:00:04.0: channel error register unreachable > > > ioatdma 0000:00:04.0: channel enumeration error > > > ioatdma 0000:00:04.0: Intel(R) I/OAT DMA Engine init failed > > > ioatdma 0000:00:04.1: channel error register unreachable > > > ioatdma 0000:00:04.1: channel enumeration error > > > ioatdma 0000:00:04.1: Intel(R) I/OAT DMA Engine init failed > > > ... > > > ioatdma 0000:00:04.7: channel error register unreachable > > > ioatdma 0000:00:04.7: channel enumeration error > > > ioatdma 0000:00:04.7: Intel(R) I/OAT DMA Engine init failed > > > mei_me 0000:00:16.0: initialization failed. > > > > > > There are 8 I/OAT DMA controllers on the Haswell-E chipset: > > > 8086:2f20 ~ 8086:2f27 > > > 80:04.0 System peripheral: Intel Corporation Haswell-E DMA > > > Channel 0 (rev 02) > > > 80:04.1 System peripheral: Intel Corporation Haswell-E DMA > > > Channel 1 (rev 02) > > > 80:04.2 System peripheral: Intel Corporation Haswell-E DMA > > > Channel 2 (rev 02) > > > 80:04.3 System peripheral: Intel Corporation Haswell-E DMA > > > Channel 3 (rev 02) > > > 80:04.4 System peripheral: Intel Corporation Haswell-E DMA > > > Channel 4 (rev 02) > > > 80:04.5 System peripheral: Intel Corporation Haswell-E DMA > > > Channel 5 (rev 02) > > > 80:04.6 System peripheral: Intel Corporation Haswell-E DMA > > > Channel 6 (rev 02) > > > 80:04.7 System peripheral: Intel Corporation Haswell-E DMA > > > Channel 7 (rev 02) > > > > > > Analysis: > > > The bug happens when the driver is resetting DMA controller, this > > > is > > > the sequence: The function, ioat_pci_probe, is called when the > > > DMA > > > controller is detected by the PCI bus. Then, > > > ioat3_dma_probe -> ioat_probe -> ioat2_enumerate_channels -> > > > ioat3_reset_hw. The following code can be found in the > > > ioat3_reset_hw: > > > > > > drivers/dma/ioat/dma_v3.c: > > >         chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET); > > >         writel(chanerr, chan->reg_base + IOAT_CHANERR_OFFSET); > > > ... > > >         err = pci_read_config_dword(pdev, > > > IOAT_PCI_CHANERR_INT_OFFSET, &chanerr); > > > if (err) { > > > dev_err(&pdev->dev, > > > "channel error register unreachable\n"); > > > return err; > > > } > > > > > > Obviously, there are something wrong in the channel error > > > register > > > reset process. Then all the way back to ioat_probe(). Because the > > > error happens, the dma->chancnt will be set to 0: > > > > > > drivers/dma/ioat/dma.c: > > >         if (!dma->chancnt) { > > >                 dev_err(dev, "channel enumeration error\n"); > > >                 goto err_setup_interrupts; > > >         } > > > > > > Finally back to ioat_pci_probe: > > > > > > drivers/dma/ioat/pci.c: > > >                 err = ioat3_dma_probe(device, ioat_dca_enabled); > > >         else > > >                 return -ENODEV; > > > > > >         if (err) { > > >                 dev_err(dev, "Intel(R) I/OAT DMA Engine init > > > failed\n"); > > >                 return -ENODEV; > > -- > > ~Vinod