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Date: Sat, 14 May 2016 14:08:54 +0200
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
To: "<netdev@...r.kernel.org>" <netdev@...r.kernel.org>,
Francois Romieu <romieu@...zoreil.com>
Cc: Ricardo Salveti <ricardo.salveti@...aro.org>,
Leif Lindholm <leif.lindholm@...aro.org>,
G Gregory <graeme.gregory@...aro.org>,
Amit Kucheria <amit.kucheria@...aro.org>,
"David S. Miller" <davem@...emloft.net>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Realtek linux nic maintainers <nic_swsd@...ltek.com>
Subject: Re: [PATCH] r8169: default to 64-bit DMA on recent PCIe chips
On 14 May 2016 at 12:41, Ard Biesheuvel <ard.biesheuvel@...aro.org> wrote:
> The current logic around the 'use_dac' module parameter prevents the
> r81969 driver from being loadable on 64-bit systems without any RAM
> below 4 GB when the parameter is left at its default value.
>
> So introduce a new default value -1 which indicates that 64-bit DMA
> should be enabled on sufficiently recent PCIe chips, i.e., versions
> RTL_GIGA_MAC_VER_18 or later. Explicit param values of 0 or 1 retain
> the existing behavior of unconditionally enabling/disabling 64-bit DMA
> on 64-bit architectures (i.e., regardless of the type and version of the
> chip)
>
> Since PCIe chips do not need to CPlusCmd Dual Address Cycle to be set,
> make that conditional on the device type as well.
>
> Cc: Realtek linux nic maintainers <nic_swsd@...ltek.com>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> ---
>
> This is a followup to 'r8169: default to 64-bit DMA on systems without memory
> below 4 GB' [1]. At the request of Francois, this version bases the decision
> whether to use 64-bit DMA by default on whether the device is PCIe and
> sufficiently recent, rather than whether the platform requires 64-bit DMA
> because it does not have any memory below 4 GB to begin with. This is safer,
> since it will prevent the use of such problematic cards on these platforms.
>
> [1] http://article.gmane.org/gmane.linux.network/412246
>
> drivers/net/ethernet/realtek/r8169.c | 48 +++++++++++---------
> 1 file changed, 27 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
> index 94f08f1e841c..80bb8ea265ad 100644
> --- a/drivers/net/ethernet/realtek/r8169.c
> +++ b/drivers/net/ethernet/realtek/r8169.c
> @@ -345,7 +345,7 @@ static const struct pci_device_id rtl8169_pci_tbl[] = {
> MODULE_DEVICE_TABLE(pci, rtl8169_pci_tbl);
>
> static int rx_buf_sz = 16383;
> -static int use_dac;
> +static int use_dac = -1;
> static struct {
> u32 msg_enable;
> } debug = { -1 };
> @@ -8224,20 +8224,6 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> goto err_out_mwi_2;
> }
>
> - tp->cp_cmd = 0;
> -
> - if ((sizeof(dma_addr_t) > 4) &&
> - !pci_set_dma_mask(pdev, DMA_BIT_MASK(64)) && use_dac) {
> - tp->cp_cmd |= PCIDAC;
> - dev->features |= NETIF_F_HIGHDMA;
> - } else {
> - rc = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
> - if (rc < 0) {
> - netif_err(tp, probe, dev, "DMA configuration failed\n");
> - goto err_out_free_res_3;
> - }
> - }
> -
> /* ioremap MMIO region */
> ioaddr = ioremap(pci_resource_start(pdev, region), R8169_REGS_SIZE);
> if (!ioaddr) {
> @@ -8247,11 +8233,30 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> }
> tp->mmio_addr = ioaddr;
>
> + /* Identify chip attached to board */
> + rtl8169_get_mac_version(tp, dev, cfg->default_ver);
> +
> if (!pci_is_pcie(pdev))
> netif_info(tp, probe, dev, "not PCI Express\n");
>
> - /* Identify chip attached to board */
> - rtl8169_get_mac_version(tp, dev, cfg->default_ver);
The reordering above is actually unnecessary, it crept in inadvertently.
> + tp->cp_cmd = 0;
> +
> + if ((sizeof(dma_addr_t) > 4) &&
> + (use_dac == 1 || (use_dac == -1 && pci_is_pcie(pdev) &&
> + tp->mac_version >= RTL_GIGA_MAC_VER_18)) &&
> + !pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {
> +
> + /* CPlusCmd Dual Access Cycle is only needed for non-PCIe */
> + if (!pci_is_pcie(pdev))
> + tp->cp_cmd |= PCIDAC;
> + dev->features |= NETIF_F_HIGHDMA;
> + } else {
> + rc = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
> + if (rc < 0) {
> + netif_err(tp, probe, dev, "DMA configuration failed\n");
> + goto err_out_unmap_4;
> + }
> + }
>
> rtl_init_rxcfg(tp);
>
> @@ -8412,12 +8417,12 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> &tp->counters_phys_addr, GFP_KERNEL);
> if (!tp->counters) {
> rc = -ENOMEM;
> - goto err_out_msi_4;
> + goto err_out_msi_5;
> }
>
> rc = register_netdev(dev);
> if (rc < 0)
> - goto err_out_cnt_5;
> + goto err_out_cnt_6;
>
> pci_set_drvdata(pdev, dev);
>
> @@ -8451,12 +8456,13 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> out:
> return rc;
>
> -err_out_cnt_5:
> +err_out_cnt_6:
> dma_free_coherent(&pdev->dev, sizeof(*tp->counters), tp->counters,
> tp->counters_phys_addr);
> -err_out_msi_4:
> +err_out_msi_5:
> netif_napi_del(&tp->napi);
> rtl_disable_msi(pdev, tp);
> +err_out_unmap_4:
> iounmap(ioaddr);
> err_out_free_res_3:
> pci_release_regions(pdev);
> --
> 2.7.4
>
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