From mboxrd@z Thu Jan 1 00:00:00 1970 From: mike.looijmans@topic.nl (Mike Looijmans) Date: Thu, 7 May 2015 14:07:25 +0200 Subject: [PATCH] arm/mm/dma-mapping.c: Add arm_coherent_dma_mmap In-Reply-To: <1431000019-7483-1-git-send-email-mike.looijmans@topic.nl> References: <1431000019-7483-1-git-send-email-mike.looijmans@topic.nl> Message-ID: <554B557D.10005@topic.nl> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org ?Oops, "arch/arm/boot/dts/topic-dyplo.dtsi" should not have been in there. Will send a v2 patch to correct that. On 07-05-15 14:00, Mike Looijmans wrote: > When dma-coherent transfers are enabled, the mmap call must > not change the pg_prot flags in the vma struct. > > Split the arm_dma_mmap into a common and specific parts, > and add a "arm_coherent_dma_mmap" implementation that does > not alter the page protection flags. > > Tested on a topic-miami board (Zynq) using the ACP port > to transfer data between FPGA and CPU using the Dyplo > framework. Without this patch, byte-wise access to mmapped > coherent DMA memory was about 20x slower because of the > memory being marked as non-cacheable, and transfer speeds > would not exceed 240MB/s. > > After this patch, the mapped memory is cacheable and the > transfer speed is again 600MB/s (limited by the FPGA) when > the data is in the L2 cache, while data integrity is being > maintained. > > The patch has no effect on non-coherent DMA. > > Signed-off-by: Mike Looijmans > --- > arch/arm/boot/dts/topic-dyplo.dtsi | 1 + > arch/arm/mm/dma-mapping.c | 32 +++++++++++++++++++++++++------- > 2 files changed, 26 insertions(+), 7 deletions(-) Kind regards, Mike Looijmans System Expert TOPIC Embedded Products Eindhovenseweg 32-C, NL-5683 KH Best Postbus 440, NL-5680 AK Best Telefoon: +31 (0) 499 33 69 79 Telefax: +31 (0) 499 33 69 70 E-mail: mike.looijmans at topicproducts.com Website: www.topicproducts.com Please consider the environment before printing this e-mail