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From: "Théo Lebrun" <theo.lebrun@bootlin.com>
To: Andrew Lunn <andrew+netdev@lunn.ch>,
	 "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	 Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,  Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	 Conor Dooley <conor+dt@kernel.org>,
	 Nicolas Ferre <nicolas.ferre@microchip.com>,
	 Claudiu Beznea <claudiu.beznea@tuxon.dev>,
	 Geert Uytterhoeven <geert@linux-m68k.org>,
	 Harini Katakam <harini.katakam@xilinx.com>,
	 Richard Cochran <richardcochran@gmail.com>,
	 Russell King <linux@armlinux.org.uk>
Cc: netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
	"Tawfik Bayouk" <tawfik.bayouk@mobileye.com>,
	"Théo Lebrun" <theo.lebrun@bootlin.com>,
	"Sean Anderson" <sean.anderson@linux.dev>
Subject: [PATCH net v3 07/16] net: macb: avoid double endianness swap in macb_set_hwaddr()
Date: Fri, 08 Aug 2025 18:52:39 +0200	[thread overview]
Message-ID: <20250808-macb-fixes-v3-7-08f1fcb5179f@bootlin.com> (raw)
In-Reply-To: <20250808-macb-fixes-v3-0-08f1fcb5179f@bootlin.com>

writel() does a CPU->LE conversion. Drop manual cpu_to_le*() calls.

On little-endian system:
 - cpu_to_le32() is a no-op (LE->LE),
 - writel() is a no-op (LE->LE),
 - dev_addr will therefore not be swapped and written as-is.

On big-endian system:
 - cpu_to_le32() is a swap (BE->LE),
 - writel() is a swap (BE->LE),
 - dev_addr will therefore be swapped twice and written as a BE value.

This was found using sparse:
   ⟩ make C=2 drivers/net/ethernet/cadence/macb_main.o
   warning: incorrect type in assignment (different base types)
      expected unsigned int [usertype] bottom
      got restricted __le32 [usertype]
   warning: incorrect type in assignment (different base types)
      expected unsigned short [usertype] top
      got restricted __le16 [usertype]
   ...

Fixes: 89e5785fc8a6 ("[PATCH] Atmel MACB ethernet driver")
Reviewed-by: Sean Anderson <sean.anderson@linux.dev>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 1e19ebcaf3810ca87729bad0ef0e13db49c548e4..4d8b4b764e0d5768a91f72fb6a5642f755ef3a5b 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -274,9 +274,9 @@ static void macb_set_hwaddr(struct macb *bp)
 	u32 bottom;
 	u16 top;
 
-	bottom = cpu_to_le32(*((u32 *)bp->dev->dev_addr));
+	bottom = *((u32 *)bp->dev->dev_addr);
 	macb_or_gem_writel(bp, SA1B, bottom);
-	top = cpu_to_le16(*((u16 *)(bp->dev->dev_addr + 4)));
+	top = *((u16 *)(bp->dev->dev_addr + 4));
 	macb_or_gem_writel(bp, SA1T, top);
 
 	if (gem_has_ptp(bp)) {

-- 
2.50.1


  parent reply	other threads:[~2025-08-08 16:52 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-08 16:52 [PATCH net v3 00/16] net: macb: various fixes & cleanup Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 01/16] dt-bindings: net: cdns,macb: allow tsu_clk without tx_clk Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 02/16] dt-bindings: net: cdns,macb: sort compatibles Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 03/16] net: macb: remove illusion about TBQPH/RBQPH being per-queue Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 04/16] net: macb: move ring size computation to functions Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 05/16] net: macb: single dma_alloc_coherent() for DMA descriptors Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 06/16] net: macb: match skb_reserve(skb, NET_IP_ALIGN) with HW alignment Théo Lebrun
2025-08-08 16:52 ` Théo Lebrun [this message]
2025-08-08 16:52 ` [PATCH net v3 08/16] net: macb: use BIT() macro for capability definitions Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 09/16] net: macb: remove gap in MACB_CAPS_* flags Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 10/16] net: macb: Remove local variables clk_init and init in macb_probe() Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 11/16] net: macb: drop macb_config NULL checking Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 12/16] net: macb: simplify macb_dma_desc_get_size() Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 13/16] net: macb: simplify macb_adj_dma_desc_idx() Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 14/16] net: macb: move bp->hw_dma_cap flags to bp->caps Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 15/16] net: macb: introduce DMA descriptor helpers (is 64bit? is PTP?) Théo Lebrun
2025-08-08 16:52 ` [PATCH net v3 16/16] net: macb: sort #includes Théo Lebrun
2025-08-08 23:06 ` [PATCH net v3 00/16] net: macb: various fixes & cleanup Jakub Kicinski

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