From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 331146B0169 for ; Sun, 14 Aug 2011 03:52:43 -0400 (EDT) Date: Sun, 14 Aug 2011 08:52:05 +0100 From: Russell King - ARM Linux Subject: Re: [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings Message-ID: <20110814075205.GA4986@n2100.arm.linux.org.uk> References: <1313146711-1767-1-git-send-email-m.szyprowski@samsung.com> <1313146711-1767-8-git-send-email-m.szyprowski@samsung.com> <201108121453.05898.arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201108121453.05898.arnd@arndb.de> Sender: owner-linux-mm@kvack.org List-ID: To: Arnd Bergmann Cc: Marek Szyprowski , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, Michal Nazarewicz , Kyungmin Park , Andrew Morton , KAMEZAWA Hiroyuki , Ankita Garg , Daniel Walker , Mel Gorman , Jesse Barker , Jonathan Corbet , Shariq Hasnain , Chunsang Jeong On Fri, Aug 12, 2011 at 02:53:05PM +0200, Arnd Bergmann wrote: > On Friday 12 August 2011, Marek Szyprowski wrote: > > > > From: Russell King > > > > Steal memory from the kernel to provide coherent DMA memory to drivers. > > This avoids the problem with multiple mappings with differing attributes > > on later CPUs. > > > > Signed-off-by: Russell King > > [m.szyprowski: rebased onto 3.1-rc1] > > Signed-off-by: Marek Szyprowski > > Hi Marek, > > Is this the same patch that Russell had to revert because it didn't > work on some of the older machines, in particular those using > dmabounce? > > I thought that our discussion ended with the plan to use this only > for ARMv6+ (which has a problem with double mapping) but not on ARMv5 > and below (which don't have this problem but might need dmabounce). I thought we'd decided to have a pool of available CMA memory on ARMv6K to satisfy atomic allocations, which can grow and shrink in size, rather than setting aside a fixed amount of contiguous system memory. ARMv6 and ARMv7+ could use CMA directly, and <= ARMv5 can use the existing allocation method. Has something changed? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org