linux-kernel - [PATCH] lan743x: Remove useless DMA-32 fallback configuration

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Date:   Sun,  9 Jan 2022 16:50:19 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Bryan Whitehead <bryan.whitehead@...rochip.com>,
        UNGLinuxDriver@...rochip.com,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        netdev@...r.kernel.org
Subject: [PATCH] lan743x: 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.

Simplify code and remove some dead code accordingly.

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

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 drivers/net/ethernet/microchip/lan743x_main.c | 22 +++++++------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index 7d7647481f70..8c6390d95158 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1739,13 +1739,10 @@ static int lan743x_tx_ring_init(struct lan743x_tx *tx)
 	}
 	if (dma_set_mask_and_coherent(&tx->adapter->pdev->dev,
 				      DMA_BIT_MASK(64))) {
-		if (dma_set_mask_and_coherent(&tx->adapter->pdev->dev,
-					      DMA_BIT_MASK(32))) {
-			dev_warn(&tx->adapter->pdev->dev,
-				 "lan743x_: No suitable DMA available\n");
-			ret = -ENOMEM;
-			goto cleanup;
-		}
+		dev_warn(&tx->adapter->pdev->dev,
+			 "lan743x_: No suitable DMA available\n");
+		ret = -ENOMEM;
+		goto cleanup;
 	}
 	ring_allocation_size = ALIGN(tx->ring_size *
 				     sizeof(struct lan743x_tx_descriptor),
@@ -2284,13 +2281,10 @@ static int lan743x_rx_ring_init(struct lan743x_rx *rx)
 	}
 	if (dma_set_mask_and_coherent(&rx->adapter->pdev->dev,
 				      DMA_BIT_MASK(64))) {
-		if (dma_set_mask_and_coherent(&rx->adapter->pdev->dev,
-					      DMA_BIT_MASK(32))) {
-			dev_warn(&rx->adapter->pdev->dev,
-				 "lan743x_: No suitable DMA available\n");
-			ret = -ENOMEM;
-			goto cleanup;
-		}
+		dev_warn(&rx->adapter->pdev->dev,
+			 "lan743x_: No suitable DMA available\n");
+		ret = -ENOMEM;
+		goto cleanup;
 	}
 	ring_allocation_size = ALIGN(rx->ring_size *
 				     sizeof(struct lan743x_rx_descriptor),
-- 
2.32.0