Re: [PATCH net-next] tg3: normalize inherited M3000 register byte order

[Andrew Lunn <andrew@lunn.ch>]

On Fri, Oct 09, 2026 at 12:04:03AM +0200, Magnus Lindholm wrote:
> M3000 firmware can leave BCM5718 vendor registers byte-swapped while
> standard PCI fields retain normal byte order. Match the Fujitsu 10cf:165a
> subsystem, IKKAKU model and swapped revision/product signature before
> restoring host control; reject failed PCI accesses or register readbacks.
> 
> Keep this in probe so failures can abort initialization; SPARC firmware
> enumeration skips PCI_FIXUP_EARLY. Normal rebinds and other platforms
> retain their existing path.
> 
> Use tg3.h's MISC_HOST_CTRL_BYTE_SWAP and TG3PCI_GEN2_PRODID_ASICREV;
> the inherited state was observed on M3000 hardware.
> 
> Signed-off-by: Magnus Lindholm <linmag7@gmail.com>

> +/* M3000 firmware can leave the on-board BCM5718 registers byte-swapped. */
> +static bool tg3_is_m3000(struct pci_dev *pdev)
> +{
> +	struct device_node *root;
> +	const char *model;
> +	bool match;
> +
> +	if (pdev->vendor != PCI_VENDOR_ID_BROADCOM ||
> +	    pdev->device != TG3PCI_DEVICE_TIGON3_5718 ||
> +	    pdev->subsystem_vendor != 0x10cf ||
> +	    pdev->subsystem_device != 0x165a)
> +		return false;
> +
> +	root = of_find_node_by_path("/");
> +	match = !of_property_read_string(root, "model", &model) &&
> +		!strcmp(model, "IKKAKU");

The DT Maintainers generally don't like this.

Is there a legitimate reason you would want the bytes are swapped?

Can you not just probe the registers, and if they are swapped undo it?
Does it really need to be conditional on the machine?

	Andrew