From mboxrd@z Thu Jan 1 00:00:00 1970 From: Santosh Shilimkar Subject: Re: [PATCH 1/5] iommu/omap: Use the cache cleaning API Date: Fri, 14 Mar 2014 13:59:16 -0400 Message-ID: <53234374.8010802@ti.com> References: <1394239574-2389-1-git-send-email-laurent.pinchart@ideasonboard.com> <53226DD5.6070208@ti.com> <53232B0F.6090701@ti.com> <201403141757.48824.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201403141757.48824.arnd@arndb.de> Sender: linux-omap-owner@vger.kernel.org To: Arnd Bergmann , "Anna, Suman" Cc: Laurent Pinchart , "linux-omap@vger.kernel.org" , "iommu@lists.linux-foundation.org" , Florian Vaussard , "sakari.ailus@iki.fi" , Russell King - ARM Linux List-Id: iommu@lists.linux-foundation.org On Friday 14 March 2014 12:57 PM, Arnd Bergmann wrote: > On Friday 14 March 2014, Santosh Shilimkar wrote: >> I remember NAKing this approach in past and my stand remains same. >> The cache APIs which you are trying to use here are not suppose >> to be used outside. >> >> I think the right way to fix this is to make use of streaming APIs. >> If needed, IOMMU can have its own dma_ops for special case >> handling if any. >> >> Russell, Arnd might have more ideas. > > I have a bad feeling about using the dma-mapping API within the > IOMMU code, because that driver is also used to implement the > dma-mapping API for devices attached to the IOMMU. It's possible > that it just works. > Thats a good point. > Is the IOMMU actually designed to have page tables in noncoherent > memory? I would have expected that the iopt accesses must all be > done on dma_alloc_coherent() provided memory to guarantee proper > accesses. > At least the OMAP one seems to use non-coherent memory which will need CMO. Regards, Santosh