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. You didn't pay attention to my previous comment on this ! IOC port can be considered a micro-architecture optimization (an important one though). The main thing is hardware snooping DMA transactions which enabled IOC in first place. > Some recent SoC with ARC HS (like HSDK) allow to select bus > port (IOC or non-IOC port) for connecting DMA devices in runtime. Again you mention the port but none of your 4 patches actually touch the port itself in programming it. > 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. Why are we not doing that for the GPU as part of this series. > You also need to apply 3 following patches firstly: > https://www.mail-archive.com/linux-snps-arc at lists.infradead.org/msg03865.html > https://www.mail-archive.com/linux-snps-arc at lists.infradead.org/msg03889.html > https://www.mail-archive.com/linux-snps-arc at 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 >
