Messages in this thread | | | From | Marcus Weseloh <> | Subject | [PATCH] spi: dts: sun4i: Add support for inter-word wait cycles | Date | Thu, 19 Nov 2015 16:53:41 +0100 |
| |
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
| |