Commit 35317688 authored by Robert Hancock's avatar Robert Hancock Committed by David S. Miller
Browse files

r8169: enable 64-bit DMA by default for PCI Express devices (v2) 



Currently use of 64-bit DMA is disabled in r8169 unless the user passes the
use_dac module option. This is reasonable for conventional PCI devices where
broken chipsets may not handle dual-address-cycle transfers properly for
32-bit slots and so this may not be safe. However, PCI Express should not have
this problem and not using 64-bit DMA results in DMA transfers needlessly using
the IOMMU or SWIOTLB. Set the use_dac module parameter to a new default value of
-1 which results in 64-bit DMA being enabled by default for PCI Express devices
only.

Signed-off-by: default avatarRobert Hancock <hancockrwd@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e4fc8560

drivers/net/r8169.c

+14 −7
Original line number Diff line number Diff line
@@ -187,7 +187,7 @@ static DEFINE_PCI_DEVICE_TABLE(rtl8169_pci_tbl) = { 
MODULE_DEVICE_TABLE(pci, rtl8169_pci_tbl);



static int rx_copybreak = 200;

static int use_dac;

static int use_dac = -1;

static struct {

	u32 msg_enable;

} debug = { -1 };
@@ -511,7 +511,8 @@ MODULE_DESCRIPTION("RealTek RTL-8169 Gigabit Ethernet driver"); 
module_param(rx_copybreak, int, 0);

MODULE_PARM_DESC(rx_copybreak, "Copy breakpoint for copy-only-tiny-frames");

module_param(use_dac, int, 0);

MODULE_PARM_DESC(use_dac, "Enable PCI DAC. Unsafe on 32 bit PCI slot.");

MODULE_PARM_DESC(use_dac, "Enable PCI DAC. -1 defaults on for PCI Express only."

" Unsafe on 32 bit PCI slot.");

module_param_named(debug, debug.msg_enable, int, 0);

MODULE_PARM_DESC(debug, "Debug verbosity level (0=none, ..., 16=all)");

MODULE_LICENSE("GPL");
@@ -2973,6 +2974,7 @@ rtl8169_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) 
	void __iomem *ioaddr;

	unsigned int i;

	int rc;

	int this_use_dac = use_dac;



	if (netif_msg_drv(&debug)) {

		printk(KERN_INFO "%s Gigabit Ethernet driver %s loaded\n",
@@ -3038,8 +3040,17 @@ rtl8169_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) 


	tp->cp_cmd = PCIMulRW | RxChkSum;



	tp->pcie_cap = pci_find_capability(pdev, PCI_CAP_ID_EXP);

	if (!tp->pcie_cap)

		netif_info(tp, probe, dev, "no PCI Express capability\n");



	if (this_use_dac < 0)

		this_use_dac = tp->pcie_cap != 0;



	if ((sizeof(dma_addr_t) > 4) &&

	    !pci_set_dma_mask(pdev, DMA_BIT_MASK(64)) && use_dac) {

	    this_use_dac &&

	    !pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {

		netif_info(tp, probe, dev, "using 64-bit DMA\n");

		tp->cp_cmd |= PCIDAC;

		dev->features |= NETIF_F_HIGHDMA;

	} else {
@@ -3058,10 +3069,6 @@ rtl8169_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) 
		goto err_out_free_res_4;

	}



	tp->pcie_cap = pci_find_capability(pdev, PCI_CAP_ID_EXP);

	if (!tp->pcie_cap)

		netif_info(tp, probe, dev, "no PCI Express capability\n");



	RTL_W16(IntrMask, 0x0000);



	/* Soft reset the chip. */

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