Hello Mark, The s3c64xx SPI driver DT binding is currently broken. Commit 3146bee ("spi: s3c64xx: Added provision for dedicated cs pin") added a new "cs-gpio" property and made it a requirement in order to make the driver behave in the same way that it used to. The motivation of the offending commit was to allow boards that want to use the native chip select (instead of a GPIO) to work with the s3c64xx SPI driver. Something that was not possible before since the driver made it mandatory to specify a GPIO. Unfortunately the commit also changed the driver defaults since now besides specifying a GPIO, it makes mandatory to also specify that a GPIO is used while the default used to be the opposite. That mean that old FDT are not working anymore after 3146bee so DT backward compatibility was not ensured by that commit. This is a follow-up series from a previous one posted by Naveen Krishna [0] which attempts to solve the issue. The feedback from Naveen's series was that the patches did not provide a clear explanation about the rationale and goal of both the series as a whole and the individual changes [1]. So I tried to take Navee's series and rework them to provide an easier to understand patch series. The series is composed of the following patches: Javier Martinez Canillas (1): Revert "spi: s3c64xx: Added provision for dedicated cs pin" Naveen Krishna Chatradhi (3): spi: s3c64xx: use the generic SPI "cs-gpios" property spi: samsung: Update binding documentation ARM: DTS: fix the chip select gpios definition in the SPI nodes .../devicetree/bindings/spi/spi-samsung.txt | 8 ++-- arch/arm/boot/dts/exynos4210-smdkv310.dts | 2 +- arch/arm/boot/dts/exynos4412-trats2.dts | 2 +- arch/arm/boot/dts/exynos5250-smdk5250.dts | 2 +- drivers/spi/spi-s3c64xx.c | 54 ++++++++++------------ 5 files changed, 30 insertions(+), 38 deletions(-) Patch 01/04 reverts the offending commit since it not only broke the DT binding but also introduced a confusing "cs-gpio" property while the driver already used a property with the same name. Patch 02/04 fixes the DT binding for good by using the SPI core "cs-gpios" property to specify the chip select GPIO instead of using a custom property only used by this driver. This change breaks backward compatibility but this has been broken for more than a year and nobody complained so I think it's safe to change it again in favor of using standard DT binding properties. A benefit of Patch 02/04 is that it allows DT and legacy boards that need to use the built-in CS instead of a GPIO to work with the driver which was the original motivation of the broken commit. Patch 03/04 updates the driver binding documentation accordingly and patch 04/04 updates all the DTS board files in mainline. Best regards, Javier [0]: http://www.spinics.net/lists/linux-samsung-soc/msg34163.html [1]: http://www.spinics.net/lists/linux-samsung-soc/msg34309.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html