[U-Boot] [PATCH 1/1] USB: Fix strict aliasing in ohci-hcd

[Troy Kisky <troy.kisky@boundarydevices.com>]

On 8/14/2012 10:33 AM, Marek Vasut wrote:
> Dear Troy Kisky,
>
>> commit 5f6aa03fda2a0a79940765865c1e4266be8a75f8
>>      USB: Fix complaints about strict aliasing in OHCI-HCD
>>
>> tried to fix this, but gcc4.4 still complains. So, this
>> patch basically reverts the above and does a simpler fix.
>>
>> also, the above commit incorrectly changed
>> 	/* corresponds to data_buf[4-7] */
>> 	datab [1] = 0;
>> to
>>
>> 	/* corresponds to databuf.u8[4-7] */
>> 	databuf.u8[1] = 0;
>>
>> This patch also fixes that.
>>
>> Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
>> ---
>>   drivers/usb/host/ohci-hcd.c |   70
>> +++++++++++++++++++------------------------ 1 file changed, 31
>> insertions(+), 39 deletions(-)
>>
>> diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
>> index d24f2f1..9f47351 100644
>> --- a/drivers/usb/host/ohci-hcd.c
>> +++ b/drivers/usb/host/ohci-hcd.c
>> @@ -1261,19 +1261,11 @@ static int ohci_submit_rh_msg(struct usb_device
>> *dev, unsigned long pipe, int leni = transfer_len;
>>   	int len = 0;
>>   	int stat = 0;
>> -	__u32 datab[4];
>> -	union {
>> -		void *ptr;
>> -		__u8 *u8;
>> -		__u16 *u16;
>> -		__u32 *u32;
>> -	} databuf;
>>   	__u16 bmRType_bReq;
>>   	__u16 wValue;
>>   	__u16 wIndex;
>>   	__u16 wLength;
>> -
>> -	databuf.u32 = (__u32 *)datab;
>> +	ALLOC_ALIGN_BUFFER(__u8, databuf, 16, sizeof(u32));
> Ok, pardon my sloppiness in reviews ... but why not alloc this cache aligned?
> That way we'd also circumvent the issues with caches we'd eventually hit anyway.
>
> [...]
>
> The rest is OK.
>


Line 1464 has

     if (data != databuf)
         memcpy(data, databuf, len);

So as far as I can tell, databuf is always copied and there are no cache 
issues to circumvent.
But I have no complaint if you desire to cacheline aligned anyway...


Troy