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| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2023-12-08 20:02:55 +0300 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2023-12-08 20:50:00 +0300 |
| commit | 8bc2a3634b87e2235535b5527f83ff529df68b56 (patch) | |
| tree | 4c61c5005fca52087758b24f750d7db7c0317973 | |
| parent | c3aeaf2f0ec8af93189488bda3928a1ac7752388 (diff) | |
| download | linux-8bc2a3634b87e2235535b5527f83ff529df68b56.tar.xz | |
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>
| -rw-r--r-- | Documentation/spi/pxa2xx.rst | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/Documentation/spi/pxa2xx.rst b/Documentation/spi/pxa2xx.rst index 143f1df83f79..19479b801826 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 |