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 implicitly, but only if setting a 32-bit DMA mask
has failed earlier. This should prevent any regressions like the ones
caused by previous attempts to change this code.
Cc: Realtek linux nic maintainers <nic_s...@realtek.com>
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
---
drivers/net/ethernet/realtek/r8169.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/realtek/r8169.c
b/drivers/net/ethernet/realtek/r8169.c
index 94f08f1e841c..a49e8a58e539 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 };
@@ -859,7 +859,8 @@ struct rtl8169_private {
MODULE_AUTHOR("Realtek and the Linux r8169 crew <netdev@vger.kernel.org>");
MODULE_DESCRIPTION("RealTek RTL-8169 Gigabit Ethernet driver");
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. Unsafe on 32 bit PCI slot (default -1: enable on
64-bit archs only if needed");
module_param_named(debug, debug.msg_enable, int, 0);
MODULE_PARM_DESC(debug, "Debug verbosity level (0=none, ..., 16=all)");
MODULE_LICENSE("GPL");
@@ -8226,12 +8227,16 @@ static int rtl_init_one(struct pci_dev *pdev, const
struct pci_device_id *ent)
tp->cp_cmd = 0;
+ /* Tentatively set the DMA mask to 32 bits. This may fail
+ * on 64-bit architectures without any RAM below 4 GB.
+ */
+ rc = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
if ((sizeof(dma_addr_t) > 4) &&
- !pci_set_dma_mask(pdev, DMA_BIT_MASK(64)) && use_dac) {
+ (use_dac == 1 || (use_dac == -1 && rc < 0)) &&
+ !pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {
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;
--
2.7.4
