From: Christoph Hellwig Subject: Re: [RFC PATCH 1/4] dma-mapping: Generalise dma_32bit_limit flag Date: Tue, 10 Jul 2018 20:04:33 +0200 Message-ID: <20180710180433.GB26285@lst.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Robin Murphy Cc: devicetree@vger.kernel.org, lorenzo.pieralisi@arm.com, gregkh@linuxfoundation.org, joro@8bytes.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, hanjun.guo@linaro.org, sudeep.holla@arm.com, frowand.list@gmail.com, hch@lst.de, linux-arm-kernel@lists.infradead.org, m.szyprowski@samsung.com List-Id: linux-acpi@vger.kernel.org On Tue, Jul 10, 2018 at 06:17:16PM +0100, Robin Murphy wrote: > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 8be8106270c2..95e185347e34 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -183,7 +183,7 @@ int dma_direct_supported(struct device *dev, u64 mask) > * Various PCI/PCIe bridges have broken support for > 32bit DMA even > * if the device itself might support it. > */ > - if (dev->dma_32bit_limit && mask > DMA_BIT_MASK(32)) > + if (dev->bus_dma_mask && mask > dev->bus_dma_mask) > return 0; The comment above this check needs an updated (or just be removed). Also we still have a few architectures not using dma-direct. I guess most were doing fine without such limits anyway, but at least arm will probably need an equivalent check.