From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ira Snyder Subject: Re: [PATCH RFC v5] net: add PCINet driver Date: Thu, 15 Jan 2009 08:54:00 -0800 Message-ID: <20090115165359.GA2230@ovro.caltech.edu> References: <20090107195052.GA24981@ovro.caltech.edu> <200901131842.54688.arnd@arndb.de> <20090115001251.GA10745@ovro.caltech.edu> <200901151358.34250.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Rusty Russell , David Miller , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, shemminger@vyatta.com, netdev@vger.kernel.org To: Arnd Bergmann Return-path: Received: from ovro.ovro.caltech.edu ([192.100.16.2]:33826 "EHLO ovro.ovro.caltech.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752407AbZAOQyC (ORCPT ); Thu, 15 Jan 2009 11:54:02 -0500 Content-Disposition: inline In-Reply-To: <200901151358.34250.arnd@arndb.de> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Jan 15, 2009 at 01:58:33PM +0100, Arnd Bergmann wrote: > On Thursday 15 January 2009, Ira Snyder wrote: > > > The only problem with that is that you cannot route interrupts from the > > DMA controller over PCI with the PowerPC core running. Which makes it > > mostly useless for this case. > > If the host supports MSI, you can simply program the DMA controller to > write the correct message to the inbound address of the MSI interrupt > controller! > > All modern host systems should have MSI, as this is required by the > PCIe specification, but it still somewhat limits the choice of your > hosts. > These are PCI boards, not PCIe. The host computers are all Pentium3-M systems. I tried enabling MSI on the Freescale boards in the driver, by calling pci_enable_msi() during probe(), and it failed. I'm pretty sure I can't do MSI. I'll keep thinking about how to manage the DMA. Feel free to toss around any ideas you have, though. Ira