From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [RFC] skge: limit DMA to 32 bit Date: Tue, 21 Sep 2010 08:02:53 -0700 Message-ID: <20100921080253.3d89d60a@nehalam> References: <20100921071518.GA9081@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Stanislaw Gruszka Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:54448 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752257Ab0IUPDZ (ORCPT ); Tue, 21 Sep 2010 11:03:25 -0400 In-Reply-To: <20100921071518.GA9081@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 21 Sep 2010 09:15:19 +0200 Stanislaw Gruszka wrote: > We have old fedora bug report about not working skge device on some > Gigabyte motherboard: > https://bugzilla.redhat.com/show_bug.cgi?id=447489 > > In dmesg there are messages: > > skge 0000:02:0b.0: PCI error cmd=0x7 status=0x22b0 > skge 0000:02:0b.0: unable to clear error (so ignoring them) > > Status value 0x22b0 include PCI_STATUS_REC_MASTER_ABORT bit set, what > mean that DMA transfer on PCI bus was aborted. > > I provided to user modified driver with module parameter, that allow > to experiment with different dma_mask's. He told that maximum working > dma_mask for him is 32 bits set. > > Is 32bit DMA limit for every skge device acceptable patch? No. The device does support 64 bit DMA, the problem is a crap implementation of the device the motherboard. Therefore a PCI quirk or module parameter is a better solution.