From 8bc2a3634b87e2235535b5527f83ff529df68b56 Mon Sep 17 00:00:00 2001 From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Date: Fri, 8 Dec 2023 19:02:55 +0200 Subject: [PATCH] spi: pxa2xx: Update DMA mapping and using logic in the documentation Update DMA mapping and using logic in the documentation to follow what the code does. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20231208170436.3309648-3-andriy.shevchenko@linux.intel.com Signed-off-by: Mark Brown <broonie@kernel.org> --- Documentation/spi/pxa2xx.rst | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/Documentation/spi/pxa2xx.rst b/Documentation/spi/pxa2xx.rst index 143f1df83f793..19479b801826c 100644 --- a/Documentation/spi/pxa2xx.rst +++ b/Documentation/spi/pxa2xx.rst @@ -193,17 +193,14 @@ mode supports both coherent and stream based DMA mappings. The following logic is used to determine the type of I/O to be used on a per "spi_transfer" basis:: - if !enable_dma then - always use PIO transfers + if spi_message.len > 65536 then + if spi_message.is_dma_mapped or rx_dma_buf != 0 or tx_dma_buf != 0 then + reject premapped transfers - if spi_message.len > 8191 then print "rate limited" warning use PIO transfers - if spi_message.is_dma_mapped and rx_dma_buf != 0 and tx_dma_buf != 0 then - use coherent DMA mode - - if rx_buf and tx_buf are aligned on 8 byte boundary then + if enable_dma and the size is in the range [DMA burst size..65536] then use streaming DMA mode otherwise -- 2.30.2