e1000e: Remove useless DMA-32 fallback configuration

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 635a959..4f6ee5c 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -7385,9 +7385,9 @@ static int e1000_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
        resource_size_t flash_start, flash_len;
        static int cards_found;
        u16 aspm_disable_flag = 0;
-       int bars, i, err, pci_using_dac;
        u16 eeprom_data = 0;
        u16 eeprom_apme_mask = E1000_EEPROM_APME;
+       int bars, i, err;
        s32 ret_val = 0;
 
        if (ei->flags2 & FLAG2_DISABLE_ASPM_L0S)
@@ -7401,17 +7401,11 @@ static int e1000_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
        if (err)
                return err;
 
-       pci_using_dac = 0;
        err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
-       if (!err) {
-               pci_using_dac = 1;
-       } else {
-               err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
-               if (err) {
-                       dev_err(&pdev->dev,
-                               "No usable DMA configuration, aborting\n");
-                       goto err_dma;
-               }
+       if (err) {
+               dev_err(&pdev->dev,
+                       "No usable DMA configuration, aborting\n");
+               goto err_dma;
        }
 
        bars = pci_select_bars(pdev, IORESOURCE_MEM);
@@ -7547,10 +7541,8 @@ static int e1000_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
        netdev->priv_flags |= IFF_UNICAST_FLT;
 
-       if (pci_using_dac) {
-               netdev->features |= NETIF_F_HIGHDMA;
-               netdev->vlan_features |= NETIF_F_HIGHDMA;
-       }
+       netdev->features |= NETIF_F_HIGHDMA;
+       netdev->vlan_features |= NETIF_F_HIGHDMA;
 
        /* MTU range: 68 - max_hw_frame_size */
        netdev->min_mtu = ETH_MIN_MTU;