[U-Boot] [PATCH 3/3] arm: at91: ether: Prepare for mach-types.h changes

[Reinhard Meyer]

Dear Igor Grinberg,

> at91 ethernet module used machine_is_cbs337()  macro for board specific
> Linux compatibility issue.
> Use compile time defines instead.
>
> Signed-off-by: Igor Grinberg<grinberg at compulab.co.il>
> ---
>   arch/arm/cpu/arm920t/at91rm9200/ether.c |   18 +++++++++---------
>   1 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm/cpu/arm920t/at91rm9200/ether.c b/arch/arm/cpu/arm920t/at91rm9200/ether.c
> index e1cdeba..4aeb883 100644
> --- a/arch/arm/cpu/arm920t/at91rm9200/ether.c
> +++ b/arch/arm/cpu/arm920t/at91rm9200/ether.c
> @@ -201,15 +201,15 @@ int eth_init (bd_t * bd)
>   	 * that MicroMonitor behavior so we avoid needing to make such OS code
>   	 * care about which bootloader was used.
>   	 */
> -	if (machine_is_csb337()) {
> -		p_mac->EMAC_SA2H = (enetaddr[0]<<   8) | (enetaddr[1]);
> -		p_mac->EMAC_SA2L = (enetaddr[2]<<  24) | (enetaddr[3]<<  16)
> -				 | (enetaddr[4]<<   8) | (enetaddr[5]);
> -	} else {
> -		p_mac->EMAC_SA2L = (enetaddr[3]<<  24) | (enetaddr[2]<<  16)
> -				 | (enetaddr[1]<<   8) | (enetaddr[0]);
> -		p_mac->EMAC_SA2H = (enetaddr[5]<<   8) | (enetaddr[4]);
> -	}
> +#ifdef CONFIG_MACH_CSB337
> +	p_mac->EMAC_SA2H = (enetaddr[0]<<   8) | (enetaddr[1]);
> +	p_mac->EMAC_SA2L = (enetaddr[2]<<  24) | (enetaddr[3]<<  16)
> +		| (enetaddr[4]<<   8) | (enetaddr[5]);
> +#else
> +	p_mac->EMAC_SA2L = (enetaddr[3]<<  24) | (enetaddr[2]<<  16)
> +		| (enetaddr[1]<<   8) | (enetaddr[0]);
> +	p_mac->EMAC_SA2H = (enetaddr[5]<<   8) | (enetaddr[4]);
> +#endif
>
>   	p_mac->EMAC_RBQP = (long) (&rbfdt[0]);
>   	p_mac->EMAC_RSR&= ~(AT91C_EMAC_RSR_OVR | AT91C_EMAC_REC | AT91C_EMAC_BNA);

There is nothing wrong with your patch itself, but it let me to take a closer look at the
reasoning of why there is a machine dependency. The full code at this section is:

	eth_getenv_enetaddr("ethaddr", enetaddr);

	/* The CSB337 originally used a version of the MicroMonitor bootloader
	 * which saved Ethernet addresses in the "wrong" order.  Operating
	 * systems (like Linux) know this, and apply a workaround.  Replicate
	 * that MicroMonitor behavior so we avoid needing to make such OS code
	 * care about which bootloader was used.
	 */
	if (machine_is_csb337()) {
		p_mac->EMAC_SA2H = (enetaddr[0] <<  8) | (enetaddr[1]);
		p_mac->EMAC_SA2L = (enetaddr[2] << 24) | (enetaddr[3] << 16)
				 | (enetaddr[4] <<  8) | (enetaddr[5]);
	} else {
		p_mac->EMAC_SA2L = (enetaddr[3] << 24) | (enetaddr[2] << 16)
				 | (enetaddr[1] <<  8) | (enetaddr[0]);
		p_mac->EMAC_SA2H = (enetaddr[5] <<  8) | (enetaddr[4]);
	}

So, for the sake of a(nother) broken bootloader and a workaround in Linux we
store the MAC address in the wrong order? What if U-Boot itself is used to make
LAN accesses?

Apart from that, it feels entirely wrong to do so. Fix the kernel to NOT do a
workaround instead should be the better approach.

Any opinions by Ben or Wolfgang on this?

Best Regards,
Reinhard