From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: new SBus related DMA warnings in 4.18+git Date: Tue, 28 Aug 2018 11:24:32 +0200 Message-ID: <20180828092432.GB12488@lst.de> References: <20180827154716.GA30492@lst.de> <20180827191518.GA26665@ravnborg.org> <20180827.134136.955064444069965259.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20180827.134136.955064444069965259.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: David Miller Cc: sparclinux-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, mroos-Y27EyoLml9s@public.gmane.org, sam-uyr5N9Q2VtJg9hUCZPvPmw@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Mon, Aug 27, 2018 at 01:41:36PM -0700, David Miller wrote: > From: Sam Ravnborg > Date: Mon, 27 Aug 2018 21:15:18 +0200 > > > Why not fix the drivers rather than papering over the fact > > that they are missing the DMA mask? > > > > We are in the lucky situation the Meelis can test any patches. > > SBUS drivers never set the mask because they never needed to and could > use the default, since SBUS IOMMUs were quite universal in nature. In addition to that the historical expectation is that you can do dma to platform_devices without setup, and for some reason sbus devices all show up as platform_devices. > I think it's more error prone to add the mask setting to every single > SBUS driver than to just have the core setup the default properly.