From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Sun, 15 Aug 2010 09:23:28 +0100 Subject: ARM: 2.6.3[45] PCI regression (IXP4xx and PXA?) In-Reply-To: <20100815144122O.fujita.tomonori@lab.ntt.co.jp> References: <20100813215413.GA21607@n2100.arm.linux.org.uk> <20100814181306U.fujita.tomonori@lab.ntt.co.jp> <20100814184605.GA1999@n2100.arm.linux.org.uk> <20100815144122O.fujita.tomonori@lab.ntt.co.jp> Message-ID: <20100815082328.GA12222@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, Aug 15, 2010 at 02:42:51PM +0900, FUJITA Tomonori wrote: > On Sat, 14 Aug 2010 19:46:05 +0100 > Russell King - ARM Linux wrote: > > > On Sat, Aug 14, 2010 at 06:30:37PM +0900, FUJITA Tomonori wrote: > > > On Fri, 13 Aug 2010 22:54:13 +0100 > > > Russell King - ARM Linux wrote: > > > > This means that when dmabounce comes to allocate the replacement > > > > buffer, it gets a buffer which won't be accessible to the DMA > > > > controller > > > > > > Really? looks like dmabounce does nothing for coherent memory that > > > dma_alloc_coherent() allocates. > > > > > > The following very hacky patch works? > > > > So what happens if you use a driver which uses dma_alloc_coherent() > > directly? Should the driver really be passed memory which is > > inaccessible to the device because its outside the host bridge PCI > > window? > > I'm not sure what you mean. > > A driver which uses dma_alloc_coherent() directly should > work. dma_alloc_coherent() allocates memory with GFP_DMA with that > patch for dmabounce devices. So the driver gets the access-able > memory. > > The memory that dma_alloc_coherent() returns should be always > consistent. We can't bounce it. All we can do is returning a memory > that a device (and its bus) can access to. > > Krzysztof, can you try the patch? Why bother when we both agree that the patch is a dirty hack? Come up with something cleaner first.