linux-kernel - [PATCH net v5 5/5] net: macb: avoid dealing with endianness in macb_set

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Message-Id: <20250910-macb-fixes-v5-5-f413a3601ce4@bootlin.com>
Date: Wed, 10 Sep 2025 18:15:34 +0200
From: Théo Lebrun <theo.lebrun@...tlin.com>
To: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Nicolas Ferre <nicolas.ferre@...rochip.com>, 
 Claudiu Beznea <claudiu.beznea@...on.dev>, 
 Geert Uytterhoeven <geert@...ux-m68k.org>, 
 Harini Katakam <harini.katakam@...inx.com>, 
 Richard Cochran <richardcochran@...il.com>, 
 Russell King <linux@...linux.org.uk>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Tawfik Bayouk <tawfik.bayouk@...ileye.com>, 
 Théo Lebrun <theo.lebrun@...tlin.com>, 
 Sean Anderson <sean.anderson@...ux.dev>
Subject: [PATCH net v5 5/5] net: macb: avoid dealing with endianness in
 macb_set_hwaddr()

bp->dev->dev_addr is of type `unsigned char *`. Casting it to a u32
pointer and dereferencing implies dealing manually with endianness,
which is error-prone.

Replace by calls to get_unaligned_le32|le16() helpers.

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]
   ...

Reviewed-by: Sean Anderson <sean.anderson@...ux.dev>
Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index fc082a7a5a313be3d58a008533c3815cb1b1639a..c16d60048185b4cb473ddfcf4633fa2f6dea20cc 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -271,12 +271,10 @@ static bool hw_is_gem(void __iomem *addr, bool native_io)

 static void macb_set_hwaddr(struct macb *bp)
 {
-	u32 bottom;
-	u16 top;
+	u32 bottom = get_unaligned_le32(bp->dev->dev_addr);
+	u16 top = get_unaligned_le16(bp->dev->dev_addr + 4);

-	bottom = cpu_to_le32(*((u32 *)bp->dev->dev_addr));
 	macb_or_gem_writel(bp, SA1B, bottom);
-	top = cpu_to_le16(*((u16 *)(bp->dev->dev_addr + 4)));
 	macb_or_gem_writel(bp, SA1T, top);

 	if (gem_has_ptp(bp)) {

-- 
2.51.0