From mboxrd@z Thu Jan 1 00:00:00 1970 From: Murali Karicheri Subject: Re: [PATCH v3 0/4] PCI: get DMA configuration from parent device Date: Thu, 8 Jan 2015 17:46:31 -0500 Message-ID: <54AF08C7.2010100@ti.com> References: <1420656594-8908-1-git-send-email-m-karicheri2@ti.com> <54ADBB89.8070503@ti.com> <1934001.D0JfDRp1gF@wuerfel> <2785994.gTZ9chGdKf@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2785994.gTZ9chGdKf@wuerfel> Sender: linux-pci-owner@vger.kernel.org To: Arnd Bergmann Cc: bhelgaas@google.com, linux-arm-kernel@lists.infradead.org, joro@8bytes.org, grant.likely@linaro.org, robh+dt@kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-pci@vger.kernel.org, will.deacon@arm.com, linux@arm.linux.org.uk List-Id: devicetree@vger.kernel.org On 01/08/2015 05:27 PM, Arnd Bergmann wrote: > On Thursday 08 January 2015 09:56:39 Arnd Bergmann wrote: >> There is another interesting case, which is a USB host controller or >> something similar behind a PCI bus. These are quite common and also >> need to be handled in some form. Let's do just PCI first for now, but >> be aware that this will come next. Should we assume that the ID that >> is required for a device is either known from the device node, or >> that it comes from a PCI device? That means for the USB case, we will >> likely need to have some custom logic. There seems to be an implicit >> assumption all over the kernel that all devices have the same IOMMU >> instance, but we can't really rely on that here. >> > > Update: I've checked the USB implementation and we are lucky because > these interactions are all done by the USB host controller, and a > USB device is not itself DMA capable. We don't have to do anything > for USB. Ok Thanks. Murali > > Arnd > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Murali Karicheri Linux Kernel, Texas Instruments