Re: [PATCH net v5 5/5] net: macb: avoid dealing with endianness in macb_set_hwaddr()

Karumanchi, Vineeth
2025-09-11T03:13:46Z

Hi Theo,

On 9/10/2025 9:45 PM, Théo Lebrun wrote:
> 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@linux.dev>
> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.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);
>

please change the order as per reverse xmas tree.

> - 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)) {
>

--
🙏 Vineeth