linux-kernel - [PATCH v2 2/2] spi: pxa2xx: Update DMA mapping and using logic in the documentation

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Date:   Fri,  8 Dec 2023 19:02:55 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Mark Brown <broonie@...nel.org>
Subject: [PATCH v2 2/2] 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@...ux.intel.com>
---
 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 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
-- 
2.43.0.rc1.1.gbec44491f096