[PATCH 1/2 v2] spi: s3c64xx: use "cs-gpios" from spi node instead of "cs-gpio"

[Doug Anderson]

Naveen / Sylwester,

On Tue, Jun 10, 2014 at 4:00 AM, Naveen Krishna Ch
<naveenkrishna.ch at gmail.com> wrote:
>> Can we support both "cs-gpio" and "cs-gpios" for backward compatibility ?
>> After your change all DTBs using the original pattern will not work with
>> new kernels any more. At least I would expect such backward compatibility
>> maintained for few kernel releases.
>
> The reason behind removing the "cs-gpio" or not providing backward
> compatibility was
>
> 1. Since spi-core started using "cs-gpios" string from spi device node
> several months ago.
>   The spi-s3c64xx.c driver is partially broken for more than 6 months.
>
> 2. Supporting "cs-gpio" would add extra bit of code.
>
> I've corrected the dts files that were using "cs-gpio" under
> "controller-data"(child node)
> to use "cs-gpio" from spi device node (parent node).
>
> I will make another version if you insist.

Yup, as near as I can tell this has been broken since (3146bee spi:
s3c64xx: Added provision for dedicated cs pin).  That landed June 25th
of 2013 into the SPI tree.

...so clearly nobody was really testing Samsung's SPI driver on ToT
Linux.  1 year of unnoticed brokenness seems like enough time that we
could do away with the old code.  If someone comes out of the woodwork
and claims a dire need to support the old binding then it can be added
then.

In-tree users of this appear to be:

arch/arm/boot/dts/exynos4210-smdkv310.dts:
 cs-gpio = <&gpc1 2 0>;
arch/arm/boot/dts/exynos4412-trats2.dts:
 cs-gpio = <&gpb 5 0>;
arch/arm/boot/dts/exynos5250-smdk5250.dts:
 cs-gpio = <&gpa2 5 0>;

...and I guess nobody has bothered using the SPI flash on those boards
for the last year?