Date: Thu, 8 Apr 2010 13:07:43 +0200
From: Daniel Mack <daniel@caiaq.de>
To: Oliver Neukum <oliver@neukum.org>
Cc: Greg KH <greg@kroah.com>, Alan Stern <stern@rowland.harvard.edu>,
       linux-kernel@vger.kernel.org, Pedro Ribeiro <pedrib@gmail.com>,
       akpm@linux-foundation.org, Greg KH <gregkh@suse.de>,
       alsa-devel@alsa-project.org, linux-usb@vger.kernel.org
Subject: Re: USB transfer_buffer allocations on 64bit systems
Message-ID: <20100408110743.GP30807@buzzloop.caiaq.de>
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 <201004080809.11756.oliver@neukum.org>
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On Thu, Apr 08, 2010 at 08:09:11AM +0200, Oliver Neukum wrote:
> Am Mittwoch, 7. April 2010 17:35:51 schrieb Daniel Mack:
> > > Alan, any objection to just using usb_buffer_alloc() for every driver?
> > > Or is that too much overhead?
> > 
> > FWIW, most drivers I've seen in the past hours use a wild mix of
> > kmalloc(), kzalloc(), kcalloc() and usb_buffer_alloc(). That should
> > really be unified.
> 
> kmalloc() & friends != usb_buffer_alloc(). They do different things.

I know. I just believe that many developers used usb_buffer_alloc() even
though they don't really need coherent DMA memory. The function's name
is misleading, and copy'n paste does the rest.

> It makes no sense to unify them. If you really need an ordinary
> buffer DMA will surely work on, this needs a third primitive.

I think it will help a lot to rename usb_buffer_alloc() in the first
place and then reconsider where coherent memory is really needed.

Daniel
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