[U-Boot] [PATCH] at91_emac: fix compile warning

[Andreas Bießmann]

Dear Reinahrd Meyer,

Am 09.06.2011 13:08, schrieb Reinhard Meyer:
> Dear Andreas Bießmann,
>> This patch removes the warning
>>
>> ---8<---
>> at91_emac.c: In function 'at91emac_write_hwaddr':
>> at91_emac.c:487:2: warning: dereferencing type-punned pointer will break strict-aliasing rules
>> --->8---
>>
>> Signed-off-by: Andreas Bießmann <andreas.devel at gmail.com>
>> ---
>> BEWARE! This patch is only compile tested!
>>
>> It is possible, that there is an endianess problem. It would be great, if one
>> could test it on real hardware!
> 
> If you have the time, can you make the same patch for macb? I can test it later on our
> hardware.

will do ..

>>
>> Reinhard, you could adopt the macb driver also to get the warning there fixed.
>> If it works on at91sam this way it would also work on at91rm9200 cause they have the
>> same endianess.
> 
> See above ;)

great ...

>>  	writel(1 << ATMEL_ID_EMAC, &pmc->pcer);
>> -	DEBUG_AT91EMAC("init MAC-ADDR %x%x \n",
>> -		cpu_to_le16(*((u16 *)(netdev->enetaddr + 4))),
>> -		cpu_to_le32(*((u32 *)netdev->enetaddr)));
>> -	writel(cpu_to_le32(*((u32 *)netdev->enetaddr)), &emac->sa2l);
>> -	writel(cpu_to_le16(*((u16 *)(netdev->enetaddr + 4))), &emac->sa2h);
>> +	DEBUG_AT91EMAC("init MAC-ADDR %02x:%02x:%02x:%02x:%02x:%02x\n",
>> +		netdev->enetaddr[5], netdev->enetaddr[4], netdev->enetaddr[3],
>> +		netdev->enetaddr[2], netdev->enetaddr[1], netdev->enetaddr[0]);
>> +	writel( (netdev->enetaddr[0] | netdev->enetaddr[1] << 8 |
>> +			netdev->enetaddr[2] << 16 | netdev->enetaddr[3] << 24),
>> +			&emac->sa2l);
> 
> OUCH, I would think by precedence rules, | comes before << !?!?!

You are wrong, try the following:

---8<---
# cat main.c
#include <stdio.h>

int main(void)
{
    unsigned int test1 = (1 << 8 | 1);
    unsigned int test2 = ((1 << 8) | 1);
    printf("test1 = %x\ntest2 = %x\n", test1, test2);
}

# gcc main.c
# ./a.out
test1 = 101
test2 = 101
--->8---

> Can you verify and supply a new patch if that holds true?

Is the test ok?

> Already applied to u-boot-atmel/master,

But why do you apply the patch, if there are questions?

regards

Andreas Bießmann