[U-Boot] [PATCH] net: See to it that sent data is aligned to the ethernet controllers wishes

[Simon Kagstrom]

On Wed, 19 Aug 2009 16:06:12 +0800
"Liu Dave-R63238" <DaveLiu at freescale.com> wrote:

> > Well, that's what the other patch I sent does (the link above), but
> > there were wishes then to handle this above the driver layer, hence
> > this patch :-)
> > 
> > I'm fine with either way, but if there are other drivers with 
> > alignment requirements, I'd prefer this variant.
> 
> I believe some Freescale's CPM/QE controllers need care the
> alignement requirement.
> 
> If you don't care the performance, you can malloc memory to
> get the aligned buffer pool in the initiaize phase,
> then use the buffer pool to resolve your alignment issue, of course
> It needs a copy, but it avoids to malloc/free buffer in run-time.

The malloc is only done once - the first time a non-aligned send is
done. After that it's just reused until the alignment requirement
exceeds the current allocation (if another interface is set
as current).

So I think the performance impact is very small.

// Simon