Dear Marc, to alleviate you of having to add all the Acked-by and Tested-by tags to this series, I've prepared a "prêt-à-porter" branch complete with all tags which you can cherry-pick or merge from. If you decide to instead apply the patches yourself, you can double-check the result by comparing it to my branch with "git range-diff". If you have any comments on the series or would like to have anything changed, please let me know. Thanks! ---------------------------------------------------------------- The following changes since commit c55be305915974db160ce6472722ff74f45b8d4e: spi: spi-fsl-dspi: Use poll mode in case the platform IRQ is missing (2019-08-23 12:01:44 +0100) are available in the git repository at: https://github.com/l1k/linux bcm2835_spi_simplex_v1 for you to fetch changes up to 37ad33d4bee27d9a24f1deffd675e327d1bb899e: spi: bcm2835: Speed up RX-only DMA transfers by zero-filling TX FIFO (2019-08-24 11:54:11 +0200) ---------------------------------------------------------------- So far the BCM2835 SPI driver cannot cope with TX-only and RX-only transfers (rx_buf or tx_buf is NULL) when using DMA: It relies on the SPI core to convert them to full-duplex transfers by allocating and DMA-mapping a dummy rx_buf or tx_buf. This costs performance. Resolve by pre-allocating reusable DMA descriptors which cyclically clear the RX FIFO (for TX-only transfers) or zero-fill the TX FIFO (for RX-only transfers). Commit fecf4ba3f248 provides some numbers for the achieved latency improvement and CPU time reduction with an SPI Ethernet controller. SPI displays should see a similar speedup. I've also made an effort to reduce peripheral and memory bus accesses. ---------------------------------------------------------------- Lukas Wunner (10): dmaengine: bcm2835: Allow reusable descriptors dmaengine: bcm2835: Allow cyclic transactions without interrupt spi: Guarantee cacheline alignment of driver-private data spi: bcm2835: Drop dma_pending flag spi: bcm2835: Work around DONE bit erratum spi: bcm2835: Cache CS register value for ->prepare_message() spi: bcm2835: Speed up TX-only DMA transfers by clearing RX FIFO dmaengine: bcm2835: Document struct bcm2835_dmadev dmaengine: bcm2835: Avoid accessing memory when copying zeroes spi: bcm2835: Speed up RX-only DMA transfers by zero-filling TX FIFO drivers/dma/bcm2835-dma.c | 38 ++++- drivers/spi/spi-bcm2835.c | 408 ++++++++++++++++++++++++++++++++++++++-------- drivers/spi/spi.c | 18 +- 3 files changed, 390 insertions(+), 74 deletions(-)
