From mboxrd@z Thu Jan 1 00:00:00 1970 From: Murali Karicheri Subject: Re: [PATCH v3 2/4] of: move of_dma_configure() to device,c to help re-use Date: Thu, 8 Jan 2015 14:26:36 -0500 Message-ID: <54AED9EC.1020703@ti.com> References: <1420656594-8908-1-git-send-email-m-karicheri2@ti.com> <1420656594-8908-3-git-send-email-m-karicheri2@ti.com> <3861625.CJ6m15sZMh@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <3861625.CJ6m15sZMh@wuerfel> Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann Cc: Rob Herring , Joerg Roedel , Grant Likely , Rob Herring , Linux IOMMU , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , Bjorn Helgaas , "linux-pci@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Will Deacon , Russell King - ARM Linux List-Id: devicetree@vger.kernel.org On 01/08/2015 03:40 AM, Arnd Bergmann wrote: > On Wednesday 07 January 2015 17:37:56 Rob Herring wrote: >> On Wed, Jan 7, 2015 at 12:49 PM, Murali Karicheri wrote: >> >>> + ret = of_dma_get_range(np,&dma_addr,&paddr,&size); >>> + if (ret< 0) { >>> + dma_addr = offset = 0; >>> + size = dev->coherent_dma_mask + 1; >> >> If coherent_dma_mask is DMA_BIT_MASK(64), then you will overflow and >> have a size of 0. There may also be a problem when the mask is only >> 32-bit type. > > The mask is always a 64-bit type, it's not optional. But you are right, > the 64-bit mask case is broken, so I guess we have to fix it differently > by always passing the smaller value into arch_setup_dma_ops and > adapting that function instead. Arnd, What is the smaller value you are referring to in the below code? between *dev->dma_mask and size from DT? But overflow can still happen when size is to be calculated in arch_setup_dma_ops() for Non DT case or when DT size is configured to be equivalent of DMA_BIT_MASK(64) + 1. Can we discuss the code change you have in mind when you get a chance? Murali > > Arnd -- Murali Karicheri Linux Kernel, Texas Instruments