From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stanislaw Gruszka Subject: [RFC] skge: limit DMA to 32 bit Date: Tue, 21 Sep 2010 09:15:19 +0200 Message-ID: <20100921071518.GA9081@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Stephen Hemminger , netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:49456 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755739Ab0IUHOR (ORCPT ); Tue, 21 Sep 2010 03:14:17 -0400 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: We have old fedora bug report about not working skge device on some Gigabyte motherboard: https://bugzilla.redhat.com/show_bug.cgi?id=447489 In dmesg there are messages: skge 0000:02:0b.0: PCI error cmd=0x7 status=0x22b0 skge 0000:02:0b.0: unable to clear error (so ignoring them) Status value 0x22b0 include PCI_STATUS_REC_MASTER_ABORT bit set, what mean that DMA transfer on PCI bus was aborted. I provided to user modified driver with module parameter, that allow to experiment with different dma_mask's. He told that maximum working dma_mask for him is 32 bits set. Is 32bit DMA limit for every skge device acceptable patch? Note, patch change possible driver DMA address space as below: - 32bit - no change, still low mem only (896MB) - 32bit-PAE - down from 36bit to low mem (896MB) - 64bit - down from 64bit to 32bit diff --git a/drivers/net/skge.c b/drivers/net/skge.c index a8a6358..1a674e3 100644 --- a/drivers/net/skge.c +++ b/drivers/net/skge.c @@ -3797,8 +3797,7 @@ static const struct net_device_ops skge_netdev_ops = { /* Initialize network device */ -static struct net_device *skge_devinit(struct skge_hw *hw, int port, - int highmem) +static struct net_device *skge_devinit(struct skge_hw *hw, int port) { struct skge_port *skge; struct net_device *dev = alloc_etherdev(sizeof(*skge)); @@ -3814,9 +3813,6 @@ static struct net_device *skge_devinit(struct skge_hw *hw, int port, dev->watchdog_timeo = TX_WATCHDOG; dev->irq = hw->pdev->irq; - if (highmem) - dev->features |= NETIF_F_HIGHDMA; - skge = netdev_priv(dev); netif_napi_add(dev, &skge->napi, skge_poll, NAPI_WEIGHT); skge->netdev = dev; @@ -3874,7 +3870,7 @@ static int __devinit skge_probe(struct pci_dev *pdev, { struct net_device *dev, *dev1; struct skge_hw *hw; - int err, using_dac = 0; + int err; err = pci_enable_device(pdev); if (err) { @@ -3890,13 +3886,9 @@ static int __devinit skge_probe(struct pci_dev *pdev, pci_set_master(pdev); - if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) { - using_dac = 1; - err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64)); - } else if (!(err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32)))) { - using_dac = 0; + err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32)); + if (!err) err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32)); - } if (err) { dev_err(&pdev->dev, "no usable DMA configuration\n"); @@ -3944,7 +3936,7 @@ static int __devinit skge_probe(struct pci_dev *pdev, (unsigned long long)pci_resource_start(pdev, 0), pdev->irq, skge_board_name(hw), hw->chip_rev); - dev = skge_devinit(hw, 0, using_dac); + dev = skge_devinit(hw, 0); if (!dev) goto err_out_led_off; @@ -3967,7 +3959,7 @@ static int __devinit skge_probe(struct pci_dev *pdev, skge_show_addr(dev); if (hw->ports > 1) { - dev1 = skge_devinit(hw, 1, using_dac); + dev1 = skge_devinit(hw, 1); if (dev1 && register_netdev(dev1) == 0) skge_show_addr(dev1); else {