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spi_master: fix master driver iram safe enviroenment

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wanlei
2023-02-23 19:43:10 +08:00
parent aff223276f
commit f11c44e55b
8 changed files with 156 additions and 17 deletions
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docs/en/api-reference/peripherals/spi_master.rst
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@@ -541,6 +541,10 @@ Cache Miss
The default config puts only the ISR into the IRAM. Other SPI related functions, including the driver itself and the callback, might suffer from cache misses and will need to wait until the code is read from flash. Select :ref:`CONFIG_SPI_MASTER_IN_IRAM` to put the whole SPI driver into IRAM and put the entire callback(s) and its callee functions into IRAM to prevent cache misses.
.. note::
SPI driver implementation is based on FreeRTOS APIs, to use :ref:`CONFIG_SPI_MASTER_IN_IRAM`, you should not enable :ref:`CONFIG_FREERTOS_PLACE_FUNCTIONS_INTO_FLASH`.
For an interrupt transaction, the overall cost is *20+8n/Fspi[MHz]* [us] for n bytes transferred in one transaction. Hence, the transferring speed is: *n/(20+8n/Fspi)*. An example of transferring speed at 8 MHz clock speed is given in the following table.
+-----------+----------------------+--------------------+------------+-------------+