[U-Boot] [PATCH 4/4] USB:gadget:designware Fix memory nonalignment issue

Amit Virdi amit.virdi at st.com
Wed Mar 7 08:14:48 CET 2012

Dear Marek,

>>>>>    }
>>>> This addresses EHCI cache problem, that's why you need bounce buffer,
>>>> right?
>>> No. The problem was we were copying data word-by-word to a non-word
>>> aligned memory in the USB gadget. So, this is different from the USB
>>> host controller issue.
>> I see ... why isn't buffer aligned by the usb stack then?
> because it might not be a requirement higher up.  i.e. it's dealing with a
> data byte stream.  forcing all higher layers to use 32bit alignment because
> this host controller requires 32bit alignment in its FIFOs is incorrect.

The usb gadget is used by the usbtty so we can receive any number of 
bytes and, as Mike explains, we cannot force 32-bit alignment.

Amit Virdi

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