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From: e99_mru@e.kth.se (Måns Rullgård)
To: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: linux-kernel@vger.kernel.org
Subject: Re: USB and DMA on Alpha with 2.6.0-test7
Date: 10 Oct 2003 13:38:42 +0200	[thread overview]
Message-ID: <yw1xwubd2ugt.fsf@quetzalcoatlite.e.kth.se> (raw)
In-Reply-To: Ivan Kokshaysky's message of "Fri, 10 Oct 2003 14:47:10 +0400"

Ivan Kokshaysky <ink@jurassic.park.msu.ru> writes:

> > Yesterday, I compiled 2.6.0-test7 for one of my Alpha boxes.  I have
> > an AX8817X based USB ethernet adaptor connected to it (it's short on
> > PCI slots), so I compiled the usbnet module.  When I loaded usbnet, I
> > got a BUG at include/asm-generic/dma-mapping.h:19.  Apparently, DMA
> > setup only works with PCI here.  How should this be fixed?  It worked
> > with -test4, albeit slowly, for other reasons.
> 
> Well, the usage of dma_supported() in usbnet.c is wrong even for i386.
> USB device doesn't do DMA, it's USB controller what does. The driver should

That's what I thought.

> check dma_mask of the parent device instead, something like this:
> 
> 	// possible with some EHCI controllers
> 	if (*udev->dev->parent->dma_mask == 0xffffffffffffffffULL)
> 		net->features |= NETIF_F_HIGHDMA;

Is that all there is to it?

-- 
Måns Rullgård
mru@users.sf.net

  reply	other threads:[~2003-10-10 11:38 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-10-10  9:22 USB and DMA on Alpha with 2.6.0-test7 Måns Rullgård
2003-10-10 10:47 ` Ivan Kokshaysky
2003-10-10 11:38   ` Måns Rullgård [this message]
2003-10-10 13:31   ` Jamie Lokier
2003-10-10 13:41     ` Ivan Kokshaysky
2003-10-10 16:41       ` Måns Rullgård
2003-10-10 17:18 David Brownell
2003-10-10 18:19 ` Ivan Kokshaysky
2003-10-10 18:45   ` Måns Rullgård
2003-10-10 18:59     ` Ivan Kokshaysky
2003-10-10 20:15       ` David Brownell
2003-10-10 19:43 ` David Brownell
2003-10-11 13:27   ` Ivan Kokshaysky
2003-10-11 16:26     ` David Brownell
2003-10-11 23:03       ` David Brownell

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