[RFC PATCH 0/4] spi: spi-fsl-spi: try to make cpu-mode transfers faster

[Rasmus Villemoes]

I doubt patches 3 and 4 are acceptable, but I'd still like to get
comments and/or alternative suggestions for making large transfers
faster.

The patches have been tested on an MPC8309 with a Cypress S25FL032P
spi-nor slave, and make various operations between 50% and 73%
faster.

We have not observed any problems, but to completely rule out the
possibility of "glitches on SPI CLK" mentioned in patch 3 would of
course require testing on a much wider set of hardware combinations.

Rasmus Villemoes (4):
  spi: spi-fsl-spi: remove always-true conditional in fsl_spi_do_one_msg
  spi: spi-fsl-spi: relax message sanity checking a little
  spi: spi-fsl-spi: allow changing bits_per_word while CS is still
    active
  spi: spi-fsl-spi: automatically adapt bits-per-word in cpu mode

 drivers/spi/spi-fsl-spi.c | 41 +++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

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2.20.1