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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: 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>
This commit is contained in:
Andy Shevchenko 2023-12-08 19:02:55 +02:00 committed by Mark Brown
parent c3aeaf2f0e
commit 8bc2a3634b
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1 changed files with 4 additions and 7 deletions
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11
Documentation/spi/pxa2xx.rst
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@ -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