Hi, On 30/07/2019 12.34, Peter Ujfalusi wrote: > Changes since v1 > (https://patchwork.kernel.org/project/linux-dmaengine/list/?series=114105&state=*) > - Added support for j721e > - Based on 5.3-rc2 > - dropped ti_sci API patch for RM management as it is already upstream > - dropped dmadev_get_slave_channel() patch, using __dma_request_channel() > - Added Rob's Reviewed-by to ringacc DT binding document patch > - DT bindings changes: > - linux,udma-mode is gone, I have a simple lookup table in the driver to flag > TR channels. > - Support for j721e > - Fix bug in of_node_put() handling in xlate function > > Changes since RFC (https://patchwork.kernel.org/cover/10612465/): > - Based on linux-next (20190506) which now have the ti_sci interrupt support > - The series can be applied and the UDMA via DMAengine API will be functional > - Included in the series: ti_sci Resource management API, cppi5 header and > driver for the ring accelerator. > - The DMAengine core patches have been updated as per the review comments for > earlier submittion. > - The DMAengine driver patch is artificially split up to 6 smaller patches it has been exactly a month ago that I have sent the v2. Before I send v3 to address Rob's pdma, prefix comment for the binding document I would like to have some feedback on the rest of the series. I believe the DMAengine core patches could be applied without the UDMA driver stack as there is now a clear user and implementation coming up for the metadata and the cached data reporting. Lokesh, Tero, Santosh: Can you look at the ringacc driver, please? Thanks, - Péter > The k3-udma driver implements the Data Movement Architecture described in > AM65x TRM (http://www.ti.com/lit/pdf/spruid7) and > j721e TRM (http://www.ti.com/lit/pdf/spruil1) > > This DMA architecture is a big departure from 'traditional' architecture where > we had either EDMA or sDMA as system DMA. > > Packet DMAs were used as dedicated DMAs to service only networking (Kesytone2) > or USB (am335x) while other peripherals were serviced by EDMA. > > In AM65x/j721e the UDMA (Unified DMA) is used for all data movment within the > SoC, tasked to service all peripherals (UART, McSPI, McASP, networking, etc). > > The NAVSS/UDMA is built around CPPI5 (Communications Port Programming Interface) > and it supports Packet mode (similar to CPPI4.1 in Keystone2 for networking) and > TR mode (similar to EDMA descriptor). > The data movement is done within a PSI-L fabric, peripherals (including the > UDMA-P) are not addressed by their I/O register as with traditional DMAs but > with their PSI-L thread ID. > > In AM65x/j721e we have two main type of peripherals: > Legacy: McASP, McSPI, UART, etc. > to provide connectivity they are serviced by PDMA (Peripheral DMA) > PDMA threads are locked to service a given peripheral, for example PSI-L thread > 0x4400/0xc400 is to service McASP0 rx/tx. > The PDMa configuration can be done via the UDMA Real Time Peer registers. > Native: Networking, security accelerator > these peripherals have native support for PSI-L. > > To be able to use the DMA the following generic steps need to be taken: > - configure a DMA channel (tchan for TX, rchan for RX) > - channel mode: Packet or TR mode > - for memcpy a tchan and rchan pair is used. > - for packet mode RX we also need to configure a receive flow to configure the > packet receiption > - the source and destination threads must be paired > - at minimum one pair of rings need to be configured: > - tx: transfer ring and transfer completion ring > - rx: free descriptor ring and receive ring > - two interrupts: UDMA-P channel interrupt and ring interrupt for tc_ring/r_ring > - If the channel is in packet mode or configured to memcpy then we only need > one interrupt from the ring, events from UDMAP is not used. > > When the channel setup is completed we only interract with the rings: > - TX: push a descriptor to t_ring and wait for it to be pushed to the tc_ring by > the UDMA-P > - RX: push a descriptor to the fd_ring and waith for UDMA-P to push it back to > the r_ring. > > Since we have FIFOs in the DMA fabric (UDMA-P, PSI-L and PDMA) which was not the > case in previous DMAs we need to report the amount of data held in these FIFOs > to clients (delay calculation for ALSA, UART FIFO flush support). > > Metadata support: > DMAengine user driver was posted upstream based/tested on the v1 of the UDMA > series: https://lkml.org/lkml/2019/6/28/20 > SA2UL is using the metadata DMAengine API. > > Note on the last patch: > In Keystone2 the networking had dedicated DMA (packet DMA) which is not the case > anymore and the DMAengine API currently missing support for the features we > would need to support networking, things like > - support for receive descriptor 'classification' > - we need to support several receive queues for a channel. > - the queues are used for packet priority handling for example, but they can be > used to have pools of descriptors for different sizes. > - out of order completion of descriptors on a channel > - when we have several queues to handle different priority packets the > descriptors will be completed 'out-of-order' > - NAPI type of operation (polling instead of interrupt driven transfer) > - without this we can not sustain gigabit speeds and we need to support NAPI > - not to limit this to networking, but other high performance operations > > It is my intention to work on these to be able to remove the 'glue' layer and > switch to DMAengine API - or have an API aside of DMAengine to have generic way > to support networking, but given how controversial and not trivial these changes > are we need something to support networking. > > The series (+DT patch to enabled UDMA/PDMA on AM65x) on top of 5.3-rc2 is > available: > https://github.com/omap-audio/linux-audio.git peter/udma/series_v2-5.3-rc2 > > Regards, > Peter > --- > Grygorii Strashko (3): > bindings: soc: ti: add documentation for k3 ringacc > soc: ti: k3: add navss ringacc driver > dmaengine: ti: k3-udma: Add glue layer for non DMAengine users > > Peter Ujfalusi (11): > dmaengine: doc: Add sections for per descriptor metadata support > dmaengine: Add metadata_ops for dma_async_tx_descriptor > dmaengine: Add support for reporting DMA cached data amount > dmaengine: ti: Add cppi5 header for UDMA > dt-bindings: dma: ti: Add document for K3 UDMA > dmaengine: ti: New driver for K3 UDMA - split#1: defines, structs, io > func > dmaengine: ti: New driver for K3 UDMA - split#2: probe/remove, xlate > and filter_fn > dmaengine: ti: New driver for K3 UDMA - split#3: alloc/free > chan_resources > dmaengine: ti: New driver for K3 UDMA - split#4: dma_device callbacks > 1 > dmaengine: ti: New driver for K3 UDMA - split#5: dma_device callbacks > 2 > dmaengine: ti: New driver for K3 UDMA - split#6: Kconfig and Makefile > > .../devicetree/bindings/dma/ti/k3-udma.txt | 170 + > .../devicetree/bindings/soc/ti/k3-ringacc.txt | 59 + > Documentation/driver-api/dmaengine/client.rst | 75 + > .../driver-api/dmaengine/provider.rst | 46 + > drivers/dma/dmaengine.c | 73 + > drivers/dma/dmaengine.h | 8 + > drivers/dma/ti/Kconfig | 22 + > drivers/dma/ti/Makefile | 2 + > drivers/dma/ti/k3-udma-glue.c | 1039 +++++ > drivers/dma/ti/k3-udma-private.c | 124 + > drivers/dma/ti/k3-udma.c | 3479 +++++++++++++++++ > drivers/dma/ti/k3-udma.h | 160 + > drivers/soc/ti/Kconfig | 17 + > drivers/soc/ti/Makefile | 1 + > drivers/soc/ti/k3-ringacc.c | 1191 ++++++ > include/dt-bindings/dma/k3-udma.h | 10 + > include/linux/dma/k3-udma-glue.h | 125 + > include/linux/dma/ti-cppi5.h | 996 +++++ > include/linux/dmaengine.h | 110 + > include/linux/soc/ti/k3-ringacc.h | 262 ++ > 20 files changed, 7969 insertions(+) > create mode 100644 Documentation/devicetree/bindings/dma/ti/k3-udma.txt > create mode 100644 Documentation/devicetree/bindings/soc/ti/k3-ringacc.txt > create mode 100644 drivers/dma/ti/k3-udma-glue.c > create mode 100644 drivers/dma/ti/k3-udma-private.c > create mode 100644 drivers/dma/ti/k3-udma.c > create mode 100644 drivers/dma/ti/k3-udma.h > create mode 100644 drivers/soc/ti/k3-ringacc.c > create mode 100644 include/dt-bindings/dma/k3-udma.h > create mode 100644 include/linux/dma/k3-udma-glue.h > create mode 100644 include/linux/dma/ti-cppi5.h > create mode 100644 include/linux/soc/ti/k3-ringacc.h > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 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