From 9a1a34f3c8612864f18a71febc134957a03eca64 Mon Sep 17 00:00:00 2001 From: Niklas Cassel Date: Mon, 24 Oct 2016 15:29:15 +0200 Subject: dmaengine: nbpfaxi: add optional max-burst property for memory reads/writes Due to a hardware bug, reading memory (from the Accelerator Coherency Port) with a burst size equal to the maximum burst size allowed by the DMA hardware's buffer size will cause a hardware hang on the ARTPEC-6 SoC, where the only solution is a manual power cycle. On ARTPEC-6, this hardware bug does not trigger when writing memory (to the Accelerator Coherency Port) with a burst size equal to the maximum burst size allowed by the DMA hardware's buffer size. To avoid this hardware hang, introduce a new optional max-burst property for memory reads. For completeness, also introduce a max-burst property for memory writes. Signed-off-by: Niklas Cassel Acked-by: Rob Herring Signed-off-by: Vinod Koul --- Documentation/devicetree/bindings/dma/nbpfaxi.txt | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'Documentation/devicetree/bindings/dma') diff --git a/Documentation/devicetree/bindings/dma/nbpfaxi.txt b/Documentation/devicetree/bindings/dma/nbpfaxi.txt index d5e2522b9ec1..d2e1e62e346a 100644 --- a/Documentation/devicetree/bindings/dma/nbpfaxi.txt +++ b/Documentation/devicetree/bindings/dma/nbpfaxi.txt @@ -23,6 +23,14 @@ Required properties #define NBPF_SLAVE_RQ_LEVEL 4 Optional properties: +- max-burst-mem-read: limit burst size for memory reads + (DMA_MEM_TO_MEM/DMA_MEM_TO_DEV) to this value, specified in bytes, rather + than using the maximum burst size allowed by the hardware's buffer size. +- max-burst-mem-write: limit burst size for memory writes + (DMA_DEV_TO_MEM/DMA_MEM_TO_MEM) to this value, specified in bytes, rather + than using the maximum burst size allowed by the hardware's buffer size. + If both max-burst-mem-read and max-burst-mem-write are set, DMA_MEM_TO_MEM + will use the lower value. You can use dma-channels and dma-requests as described in dma.txt, although they won't be used, this information is derived from the compatibility string. -- cgit v1.2.3-59-g8ed1b