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, 'highdma' is known to be true.

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>
---
 drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
index dde1cf51d0ab..0c78c0db8937 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
@@ -6608,7 +6608,6 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	static int adap_idx = 1;
 	int s_qpp, qpp, num_seg;
 	struct port_info *pi;
-	bool highdma = false;
 	enum chip_type chip;
 	void __iomem *regs;
 	int func, chip_ver;
@@ -6687,14 +6686,10 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 		return 0;
 	}
 
-	if (!dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64))) {
-		highdma = true;
-	} else {
-		err = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
-		if (err) {
-			dev_err(&pdev->dev, "no usable DMA configuration\n");
-			goto out_free_adapter;
-		}
+	err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+	if (err) {
+		dev_err(&pdev->dev, "no usable DMA configuration\n");
+		goto out_free_adapter;
 	}
 
 	pci_enable_pcie_error_reporting(pdev);
@@ -6823,7 +6818,7 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 			NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
 			NETIF_F_RXCSUM | NETIF_F_RXHASH | NETIF_F_GRO |
 			NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_CTAG_RX |
-			NETIF_F_HW_TC | NETIF_F_NTUPLE;
+			NETIF_F_HW_TC | NETIF_F_NTUPLE | NETIF_F_HIGHDMA;
 
 		if (chip_ver > CHELSIO_T5) {
 			netdev->hw_enc_features |= NETIF_F_IP_CSUM |
@@ -6841,8 +6836,6 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 				netdev->udp_tunnel_nic_info = &cxgb_udp_tunnels;
 		}
 
-		if (highdma)
-			netdev->hw_features |= NETIF_F_HIGHDMA;
 		netdev->features |= netdev->hw_features;
 		netdev->vlan_features = netdev->features & VLAN_FEAT;
 #if IS_ENABLED(CONFIG_CHELSIO_TLS_DEVICE)
-- 
2.32.0

Hello:

This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Sun,  9 Jan 2022 14:53:27 +0100 you wrote:
> 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, 'highdma' is known to be true.
> 
> Simplify code and remove some dead code accordingly.
> 
> [...]

Here is the summary with links:
  - cxgb4: Remove useless DMA-32 fallback configuration
    https://git.kernel.org/netdev/net-next/c/7fc7fc5da61b

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html