From mboxrd@z Thu Jan 1 00:00:00 1970 From: "gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org" Subject: Re: [PATCH 2/2] arm/xen: Don't use xen DMA ops when the device is protected by an IOMMU Date: Fri, 14 Mar 2014 23:56:37 +0000 Message-ID: <20140314235637.GA5687@kroah.com> References: <1392913301-25524-1-git-send-email-julien.grall@linaro.org> <1392914159.32657.18.camel@kazak.uk.xensource.com> <20140224151636.GA13489@kroah.com> <5323334F.90700@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <5323334F.90700-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Julien Grall Cc: Stefano Stabellini , Russell King , Ian Campbell , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, xen-devel-GuqFBffKawtpuQazS67q72D2FQJk+8+b@public.gmane.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Rob Landley , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On Fri, Mar 14, 2014 at 04:50:23PM +0000, Julien Grall wrote: > On 02/24/2014 08:49 PM, Stefano Stabellini wrote: > > On Mon, 24 Feb 2014, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org wrote: > > Julien is proposing to store the list of "safe" devices on an hash table > > in the Xen specific code (in arch/arm/xen/enlighten.c, see > > http://marc.info/?l=linux-kernel&m=139291370526082&w=2). > > Whenever Linux is about to do DMA, we would check in the hashtable to > > figure out whether we need to go through the swiotlb or we can simply > > use the native dma_ops. > > > > Ian and I were thinking that it would be much easier and faster to have > > a "xen_safe_device" parameter in struct device and just check for that. > > It doesn't actually need to be in struct device, it could simply be a > > flag in struct device_dma_parameters as Ian was suggesting. > > > > Julien, could you please come up with a simple patch to demonstrate the > > concept? > > Hello Stefano and Greg, > > Sorry for the late answer. I wrote a simple patch which depend on patch #1. > Let me know if it's the right direction. I have no context here, care to start the patch series over? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html