Unverified Commit 8bc2a363 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Mark Brown
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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: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231208170436.3309648-3-andriy.shevchenko@linux.intel.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent c3aeaf2f

Documentation/spi/pxa2xx.rst

+4 −7
Original line number Diff line number Diff line
@@ -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