Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754986AbZFPI4Z (ORCPT ); Tue, 16 Jun 2009 04:56:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754426AbZFPI4G (ORCPT ); Tue, 16 Jun 2009 04:56:06 -0400 Received: from sh.osrg.net ([192.16.179.4]:57131 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753040AbZFPI4E (ORCPT ); Tue, 16 Jun 2009 04:56:04 -0400 Date: Tue, 16 Jun 2009 17:55:59 +0900 To: malcolm.blaney@maptek.com.au Cc: fujita.tomonori@lab.ntt.co.jp, linux-kernel@vger.kernel.org Subject: Re: is_device_dma_capable From: FUJITA Tomonori In-Reply-To: <2e115de50906160123n20791768sd154621b0d95ca50@mail.gmail.com> References: <2e115de50906160024r7c3140d6sc8744e4362d36ef8@mail.gmail.com> <20090616171029H.fujita.tomonori@lab.ntt.co.jp> <2e115de50906160123n20791768sd154621b0d95ca50@mail.gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20090616175549Y.fujita.tomonori@lab.ntt.co.jp> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (sh.osrg.net [192.16.179.4]); Tue, 16 Jun 2009 17:56:00 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1795 Lines: 45 On Tue, 16 Jun 2009 17:53:03 +0930 Malcom Blaney wrote: > Hi Fujita, > > 2009/6/16 FUJITA Tomonori : > > You use X86_32, right? > > I have CONFIG_X86_32=y in my config file. > > > > > In 2.6.25, X86_32 and X86_64 had the own dma_alloc_coherent > > implementations; X86_32 accepted a device having dma_mask that is not > > initialized however X86_64 didn't, I think. > > > > When we merged them, we chose to prohibit a device having dma_mask > > that is not initialized. I'm not sure the DMA docs say this but IMO > > it's good to require drivers to set up dma_mask (and > > coherent_dma_mask) properly if the drivers want DMA. > > > > If you could point me in the direction of how to set these values > correctly, I would appreciate it. You hit the problem that a device that parport_pc_probe_port creates but doesn't set up the dma_mask properly, right (I'm not familiar with the driver at all so I might misunderstand something)? If so, I guess that the following patch works (only compile tested). diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c index 151bf5b..1af57b7 100644 --- a/drivers/parport/parport_pc.c +++ b/drivers/parport/parport_pc.c @@ -2271,6 +2271,9 @@ struct parport *parport_pc_probe_port(unsigned long int base, if (IS_ERR(pdev)) return NULL; dev = &pdev->dev; + + dev->coherent_dma_mask = DMA_BIT_MASK(24); + dev->dma_mask = &dev->coherent_dma_mask; } ops = kmalloc(sizeof(struct parport_operations), GFP_KERNEL); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/