From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v2 01/11] asm-generic: add dma_zone_size Date: Mon, 26 Aug 2019 09:09:39 +0200 Message-ID: <20190826070939.GD11331@lst.de> References: <20190820145821.27214-1-nsaenzjulienne@suse.de> <20190820145821.27214-2-nsaenzjulienne@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190820145821.27214-2-nsaenzjulienne@suse.de> Sender: linux-kernel-owner@vger.kernel.org To: Nicolas Saenz Julienne Cc: catalin.marinas@arm.com, hch@lst.de, wahrenst@gmx.net, marc.zyngier@arm.com, robh+dt@kernel.org, Robin Murphy , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, iommu@lists.linux-foundation.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, Arnd Bergmann , phill@raspberryi.org, f.fainelli@gmail.com, will@kernel.org, linux-kernel@vger.kernel.org, eric@anholt.net, mbrugger@suse.com, linux-rpi-kernel@lists.infradead.org, akpm@linux-foundation.org, frowand.list@gmail.com, m.szyprowski@samsung.com List-Id: devicetree@vger.kernel.org On Tue, Aug 20, 2019 at 04:58:09PM +0200, Nicolas Saenz Julienne wrote: > Some architectures have platform specific DMA addressing limitations. > This will allow for hardware description code to provide the constraints > in a generic manner, so as for arch code to properly setup it's memory > zones and DMA mask. I know this just spreads the arm code, but I still kinda hate it. MAX_DMA_ADDRESS is such an oddly defined concepts. We have the mm code that uses it to start allocating after the dma zones, but I think that would better be done using a function returning 1 << max(zone_dma_bits, 32) or so. Then we have about a handful of drivers using it that all seem rather bogus, and one of which I think are usable on arm64.