From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 2/2] dma: add Qualcomm Technologies HIDMA channel driver Date: Fri, 30 Oct 2015 23:47:46 +0100 Message-ID: <5126606.XdciyP3Dft@wuerfel> References: <1446174501-8870-1-git-send-email-okaya@codeaurora.org> <5633E442.3010003@codeaurora.org> <5633E744.6040202@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <5633E744.6040202-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Timur Tabi Cc: Sinan Kaya , dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cov-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, jcm-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Vinod Koul , Dan Williams , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On Friday 30 October 2015 16:55:16 Timur Tabi wrote: > > On 10/30/2015 04:42 PM, Sinan Kaya wrote: > >> > >> if (WARN_ON(!pdev->dev.dma_mask)) > >> return -ENXIO; > >> > >> The dma mask has to always be set by the platform code before probe() > >> is called. If it is not set, you are not allowed to perform DMA. > > > > I tested this on an ACPI platform BTW when I was working on the initial > > implementation. > > PowerPC sets the mask to 32 bits by default: > > http://lxr.free-electrons.com/ident?i=arch_setup_pdev_archdata > > Should we do something similar in ARM64? Today, we have to manually set > the DMA mask in all drivers. We set the dma mask from the 'dma-ranges' property of the parent device, but fall back to 32-bit because we did not manage to mandate this property in time for all arm64 machines to use. Arnd -- 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