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SubjectRe: [PATCH v2 0/4] ARC: allow to use IOC and non-IOC DMA devices simultaneously
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On 07/30/2018 09:26 AM, Eugeniy Paltsev wrote:
> The ARC HS processor provides an IOC port (I/O coherency bus
> interface) that allows external devices such as DMA devices
> to access memory through the cache hierarchy, providing
> coherency between I/O transactions and the complete memory
> hierarchy.
>
> Some recent SoC with ARC HS (like HSDK) allow to select bus
> port (IOC or non-IOC port) for connecting DMA devices in runtime.
>
> With this patch we can use both HW-coherent and regular DMA
> peripherals simultaneously.
>
> NOTE:
> This patch series was stress tested on HSDK with iperf3 (ethernet)
> and bonie++ (usb and sdio) in three configurations:
> * IOC enabled globaly
> * IOC disabled globaly
> * IOC enabled partially (USB & SDIO are connected via IOC AXI port,
> ethernet is connected to DDR AXI port (non-IOC port)
>
> NOTE:
> If you want to test some device without IOC it is not enough
> to remove "dma-coherent" property from dts. You had to remap this
> device to regular DDR AXI port intead of IOC AXI port.
> You also need to apply 3 following patches firstly:
> https://www.mail-archive.com/linux-snps-arc@lists.infradead.org/msg03865.html
> https://www.mail-archive.com/linux-snps-arc@lists.infradead.org/msg03889.html
> https://www.mail-archive.com/linux-snps-arc@lists.infradead.org/msg03887.html
>
> NOTE:
> We don't touch any aperture configuration in this patch series. So we
> don't switch any devices between IOC and non-IOC AXI ports on any board.
> It can be done later if it is required.
>
> Changes v1->v2 (Thanks to Christoph):
> * Don't select DMA_DIRECT_OPS explicitly as it is already selected by
> DMA_NONCOHERENT_OPS
> * Remove check for HIGHMEM pages from arch_dma_{alloc, free}
>
> Eugeniy Paltsev (4):
> ARC: DTS: mark DMA devices connected through IOC port as dma-coherent
> ARC: allow to use IOC and non-IOC DMA devices simultaneously
> ARC: IOC: panic if both IOC and ZONE_HIGHMEM enabled
> ARC: don't check for HIGHMEM pages in arch_dma_alloc
>
> arch/arc/boot/dts/axc003.dtsi | 26 ++++++++++++++++
> arch/arc/boot/dts/axc003_idu.dtsi | 26 ++++++++++++++++
> arch/arc/boot/dts/hsdk.dts | 4 +++
> arch/arc/include/asm/dma-mapping.h | 13 ++++++++
> arch/arc/mm/cache.c | 30 +++++++++---------
> arch/arc/mm/dma.c | 62 +++++++++++++++++++-------------------
> 6 files changed, 115 insertions(+), 46 deletions(-)
> create mode 100644 arch/arc/include/asm/dma-mapping.h

Apologies for the delay in getting to this - series applied and pushed to for-curr

Thx,
-Vineet


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