From: Mark Brown Date: Mon, 15 Dec 2025 01:09:50 +0000 (+0900) Subject: Support ECSPI dynamic burst feature for DMA mode X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c73618541c68f4b3c9b40de3a0f926447a9a9e72;p=thirdparty%2Fkernel%2Flinux.git Support ECSPI dynamic burst feature for DMA mode Merge series from Carlos Song : ECSPI has a low throughput because of no dynamic burst support, it transfers only one word per frame in DMA mode, causing SCLK stalls between words due to BURST_LENGTH updates. This patch set is to support ECSPI dynamic burst feature to help improve the ECSPI DMA mode performance. Performance test (spidev_test @10MHz, 4KB): Before: tx/rx ~6651.9 kbps After: tx/rx ~9922.2 kbps (~50% improvement) For compatibility with slow SPI devices, add configurable word delay in DMA mode. When word delay is set, dynamic burst is disabled and BURST_LENGTH equals word length. Also support target DMA mode with enabled dynamic burst. --- Changes since v2: * Patch1~4: no change * Patch5: remove __counted_by from *dma_data, because spi_imx struct is allocated with a fixed memory in probe, flexible array is not suitable, so just remove it to avoid the build error. Also add review-by tag * Patch6: add review-by tag Changes since v1: * Patch1~3: * Add review-by tag * Patch4: * Add review-by tag * Improve patch commit log * Patch5: * Clean up tab instead of space for dma_tx_addr and dma_rx_addr * Add __counted_by(dma_package_num) for dma_data_package *dma_data * Move temp and bytes_per_word to if() * Add comment for spi_imx_dma_rx_data_handle() and spi_imx_dma_tx_data_handle() * Use kzalloc instead of kmalloc(x, x | __GFP_ZERO) * Use sizeof(*temp) instead of BYTES_PER_32BITS_WORD in suitable place * Add comments and fix comments according to discussion * Propagate the error value of dma_mapping_error() * Use round_down() to replace DIV_ROUND_DOWN_ULL() * Improve transfer->error |= SPI_TRANS_FAIL_NO_START judgment for better readability * Patch6: * Improve patch commit log * Add READ_ONCE for spi_imx->target_aborted * Add comments for data length limit * Move data length limit to spi_imx_can_dma() Carlos Song (6): spi: imx: group spi_imx_dma_configure() with spi_imx_dma_transfer() spi: imx: introduce helper to clear DMA mode logic spi: imx: avoid dmaengine_terminate_all() on TX prep failure spi: imx: handle DMA submission errors with dma_submit_error() spi: imx: support dynamic burst length for ECSPI DMA mode spi: imx: enable DMA mode for target operation drivers/spi/spi-imx.c | 625 +++++++++++++++++++++++++++++++++++------- 1 file changed, 519 insertions(+), 106 deletions(-) -- 2.34.1 --- c73618541c68f4b3c9b40de3a0f926447a9a9e72