> -----Original Message----- > From: Koul, Vinod > Sent: Thursday, May 19, 2016 10:23 AM > To: Jiang, Dave <dave.jiang@xxxxxxxxx> > Cc: Gavin Guo <gavin.guo@xxxxxxxxxxxxx>; dmaengine@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Williams, Dan J > <dan.j.williams@xxxxxxxxx> > Subject: Re: ioatdma(Intel(R) I/OAT DMA Engine init failed) > > On Thu, May 19, 2016 at 08:19:30PM +0530, Jiang, Dave wrote: > > > -----Original Message----- > > > From: Gavin Guo [mailto:gavin.guo@xxxxxxxxxxxxx] > > > Sent: Wednesday, May 18, 2016 8:19 PM > > > To: Jiang, Dave <dave.jiang@xxxxxxxxx> > > > Cc: Koul, Vinod <vinod.koul@xxxxxxxxx>; dmaengine@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Williams, Dan J > > > <dan.j.williams@xxxxxxxxx> > > > Subject: Re: ioatdma(Intel(R) I/OAT DMA Engine init failed) > > > > > > On Thu, May 19, 2016 at 12:49 AM, Jiang, Dave <dave.jiang@xxxxxxxxx> wrote: > > > > On Wed, 2016-05-18 at 13:27 +0000, Gavin Guo wrote: > > > >> On Tue, May 17, 2016 at 6:06 PM, Vinod Koul <vinod.koul@xxxxxxxxx> > > > >> 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. > > > > > > Really thanks for your advice. :) > > > > > > I searched the internet about the extended PCI config space and found > > > the link: > > > > > > [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in > > > http://lwn.net/Articles/263288/ > > > > Can you try calling pci_enable_ext_config() in the PCI probe for your kernel? I just haven't seen this issue in the latest kernel. > > Do we need that to be called explicitly by driver, should that not be enabled > by default? It used to be but the patch seems to indicate it's an opt in thing. But what I don't get is I have never encountered this issue. > > > > > > > > > And I checked the config and found the CONFIG_PCI_MMCONFIG=y. The > > > following string also can be observed in the dmesg: > > > > > > [ 1.419853] PCI: MMCONFIG for domain 0000 [bus 00-ff] at > > > [mem0x80000000-0x8fffffff] (base 0x80000000) > > > [ 1.419855] PCI: MMCONFIG at [mem 0x80000000-0x8fffffff] reserved in E820 > > > > > > It seems the extended PCI config space is enabled. If there is > > > anything missed? > > > > > > > > > > >> > > > >> > > > > >> > > > > >> > > > > > >> > > > > > >> > > 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 > > -- > ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
