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[PATCH] spi: dts: sun4i: Add support for inter-word wait cycles

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Hi all,

the Allwinner A10/A20 SPI module supports an option to configure a number of
clock periods to wait between each word ("SPI Wait Clock Register" in the A20
manual). This is a very useful option if talking to devices which specify a
minimum amount of inter-word wait time.

I initially tried to find a way to let SPI protocol drivers specify this
option, but I couldn't find a mechanism to pass additional options to the spi
master. So I took the spi-davinci driver as an example (it implements a very
similiar functionality) and added a new devicetree property.

While testing this patch I noticed that the SPI module always adds a constant
3 clock cycles to the number set in the Wait Clock Register. That number stays
constant across many different baud rates, so I documented it in the
devicetree binding file.

One thing I am unsure of is the device example in the binding
documentation.  I used "example,dummy" as compatible... is this acceptable or
should I use a device/compatible that actually exists somewhere?

Oh... and should I split binding documentation and code changing patch?

Best regards,

  Marcus


Marcus Weseloh (1):
  spi: dts: sun4i: Add support for inter-word wait cycles using the SPI
    Wait Clock Register

 Documentation/devicetree/bindings/spi/spi-sun4i.txt | 11 +++++++++++
 drivers/spi/spi-sun4i.c                             |  7 +++++++
 2 files changed, 18 insertions(+)

-- 
1.9.1

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[PATCH] spi: dts: sun4i: Add support for inter-word wait cycles Marcus Weseloh <mweseloh42@gmail.com> - 2015-11-19 17:00 +0100
  [PATCH] spi: dts: sun4i: Add support for inter-word wait cycles using the SPI Wait Clock Register Marcus Weseloh <mweseloh42@gmail.com> - 2015-11-19 17:00 +0100
    Re: [linux-sunxi] [PATCH] spi: dts: sun4i: Add support for inter-word  wait cycles using the SPI Wait Clock Register Julian Calaby <julian.calaby@gmail.com> - 2015-11-20 00:00 +0100
      Re: [linux-sunxi] [PATCH] spi: dts: sun4i: Add support for inter-word  wait cycles using the SPI Wait Clock Register Marcus Weseloh <mweseloh42@gmail.com> - 2015-11-20 09:50 +0100
        Re: [linux-sunxi] [PATCH] spi: dts: sun4i: Add support for inter-word  wait cycles using the SPI Wait Clock Register Julian Calaby <julian.calaby@gmail.com> - 2015-11-20 11:20 +0100
          Re: [linux-sunxi] [PATCH] spi: dts: sun4i: Add support for inter-word  wait cycles using the SPI Wait Clock Register Marcus Weseloh <mweseloh42@gmail.com> - 2015-11-20 15:00 +0100
            Re: [linux-sunxi] [PATCH] spi: dts: sun4i: Add support for  inter-word wait cycles using the SPI Wait Clock Register Rob Herring <robh@kernel.org> - 2015-11-20 17:20 +0100
              Re: [linux-sunxi] [PATCH] spi: dts: sun4i: Add support for inter-word  wait cycles using the SPI Wait Clock Register Marcus Weseloh <mweseloh42@gmail.com> - 2015-11-20 17:50 +0100
                Re: [linux-sunxi] [PATCH] spi: dts: sun4i: Add support for  inter-word wait cycles using the SPI Wait Clock Register Maxime Ripard <maxime.ripard@free-electrons.com> - 2015-11-22 20:50 +0100
                Re: [linux-sunxi] [PATCH] spi: dts: sun4i: Add support for inter-word  wait cycles using the SPI Wait Clock Register Marcus Weseloh <mweseloh42@gmail.com> - 2015-11-23 10:20 +0100
    Re: [PATCH] spi: dts: sun4i: Add support for inter-word wait cycles  using the SPI Wait Clock Register Rob Herring <robh@kernel.org> - 2015-11-20 17:10 +0100

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