Patrice Chotard f3530f26f8 spi: stm32-qspi: Trigger DMA only if more than 4 bytes to transfer
In order to optimize accesses to spi flashes, trigger a DMA only
if more than 4 bytes has to be transferred.

DMA transfer preparation's cost becomes negligible above 4 bytes to
transfer. Below this threshold, indirect transfer give more throughput.

mtd_speedtest shows that page write throughtput increases :
  - from 779 to 853 KiB/s (~9.5%) with s25fl512s SPI-NOR.
  - from 5283 to 5666 KiB/s (~7.25%) with Micron SPI-NAND.

Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Link: https://lore.kernel.org/r/20210419121541.11617-3-patrice.chotard@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>
2021-04-19 14:18:43 +01:00
2021-01-24 14:27:20 +01:00
2021-03-02 17:25:46 -07:00
2021-02-26 09:41:03 -08:00
2021-02-26 09:41:03 -08:00
2021-02-26 09:41:03 -08:00
2021-03-05 17:33:41 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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