From: Peter Ujfalusi <peter.ujfalusi@ti.com> To: <vkoul@kernel.org>, <robh+dt@kernel.org> Cc: <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <dan.j.williams@intel.com>, <devicetree@vger.kernel.org> Subject: [RFC 0/3] dmaengine: Support for DMA domain controllers Date: Fri, 6 Sep 2019 17:18:13 +0300 Message-ID: <20190906141816.24095-1-peter.ujfalusi@ti.com> (raw) Hi, More and more SoC have more than one DMA controller integrated. If a device needs none slave DMA channel for operation (block copy from/to memory mapped regions for example) at the moment when they request a channel it is going to be taken from the first DMA controller which was registered, but this might be not optimal for the device. For example on AM654 we have two DMAs: main_udmap and mcu_udmap. DDR to DDR memcpy is twice as fast on main_udmap compared to mcu_udmap, while devices on MCU domain (OSPI for example) are more than twice as fast on mcu_udmap than with main_udmap. Because of probing order (mcu_udmap is probing first) modules would use mcu_udmap instead of the better main_udmap. Currently the only solution is to make a choice and disable the MEM_TO_MEM functionality on one of them which is not a great solution. With the introduction of DMA domain controllers we can utilize the best DMA controller for the job around the SoC without the need to degrade performance. If the dma-domain-controller is not present in DT or booted w/o DT the none slave channel request will work as it does today. The last patch introduces a new dma_domain_request_chan_by_mask() function and I have a define for dma_request_chan_by_mask() to avoid breaking users of the dma_request_chan_by_mask, but looking at the kernel we have small amount of users: drivers/gpu/drm/vc4/vc4_dsi.c drivers/media/platform/omap/omap_vout_vrfb.c drivers/media/platform/omap3isp/isphist.c drivers/mtd/spi-nor/cadence-quadspi.c drivers/spi/spi-ti-qspi.c If it is acceptable we can modify the parameters of dma_request_chan_by_mask() to include ther device pointer and at the same time change all of the clients by giving NULL or in case of the last two their dev. Regards, Peter --- Peter Ujfalusi (3): dt-bindings: dma: Add documentation for DMA domains dmaengine: of_dma: Function to look up the DMA domain of a client dmaengine: Support for requesting channels preferring DMA domain controller .../devicetree/bindings/dma/dma-domain.yaml | 59 +++++++++++++++++++ drivers/dma/dmaengine.c | 17 ++++-- drivers/dma/of-dma.c | 42 +++++++++++++ include/linux/dmaengine.h | 9 ++- include/linux/of_dma.h | 7 +++ 5 files changed, 126 insertions(+), 8 deletions(-) create mode 100644 Documentation/devicetree/bindings/dma/dma-domain.yaml -- Peter Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
next reply index Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-09-06 14:18 Peter Ujfalusi [this message] 2019-09-06 14:18 ` [RFC 1/3] dt-bindings: dma: Add documentation for DMA domains Peter Ujfalusi 2019-09-08 7:47 ` Peter Ujfalusi 2019-09-08 12:10 ` Vinod Koul 2019-09-09 6:30 ` Peter Ujfalusi 2019-09-12 17:03 ` Vinod Koul 2019-09-13 7:21 ` Peter Ujfalusi 2019-09-13 10:36 ` Vinod Koul 2019-09-13 12:19 ` Peter Ujfalusi 2019-09-13 13:33 ` Vinod Koul 2019-09-08 12:06 ` Vinod Koul 2019-09-09 6:00 ` Peter Ujfalusi 2019-09-06 14:18 ` [RFC 2/3] dmaengine: of_dma: Function to look up the DMA domain of a client Peter Ujfalusi 2019-09-08 12:12 ` Vinod Koul 2019-09-06 14:18 ` [RFC 3/3] dmaengine: Support for requesting channels preferring DMA domain controller Peter Ujfalusi 2019-09-08 7:46 ` Peter Ujfalusi 2019-09-08 12:15 ` Vinod Koul 2019-09-09 5:56 ` Peter Ujfalusi 2019-09-12 16:49 ` Vinod Koul -- strict thread matches above, loose matches on Subject: below -- 2019-09-06 14:17 [RFC 0/3] dmaengine: Support for DMA domain controllers Peter Ujfalusi
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