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

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Message-ID: <20190327143040.16013-1-rasmus.villemoes@prevas.dk>
Date:   Wed, 27 Mar 2019 14:30:48 +0000
From:   Rasmus Villemoes <rasmus.villemoes@...vas.dk>
To:     Mark Brown <broonie@...nel.org>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Fabio Estevam <festevam@...il.com>,
        Rasmus Villemoes <Rasmus.Villemoes@...vas.se>
Subject: [RFC PATCH 0/4] spi: spi-fsl-spi: try to make cpu-mode transfers
 faster

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(-)

-- 
2.20.1