I know this is gonna be a controversial series, but we have a usecase for this :)
This series allows an I2C bus to switch between multiple masters, i.e. a n-to-1-demuxer. This is not hot-switching because connected I2C slaves will be re-instantiated. It is meant to select the best I2C core at runtime once the task is known. Example: Prefer i2c-gpio over another I2C core because of HW errata affecting your current runtime configuration. It works by using OF_DYNAMIC and en-/disabling the i2c parent as needed. See the binding docs for more details. Because this is largely using OF_DYNAMIC, I decided to post the whole series to the dt list. Changes since RFC v1: * gracefully handle if i2c adapters are not present at runtime (driver not loaded yet) * added more documentation and examples * properly put the i2c adapters after use * respect PAGE_SIZE in sysfs_show This has been tested on a Renesas Lager board switching between i2c-gpio and two different IP cores (i2c-rcar and i2c-sh_mobile). The rebinding seems to be working as expected. However, in practice, I couldn't use the HDMI i2c slaves with another controller yet, because the rcar-du driver OOPSes when unbinding. This seems unrelated to this series because it can also be triggered via sysfs-unbind. soc-camera also had problems properly cleaning up on unbind, a patch for this already has been sent. So, this series is for sure a good test for the unbind path of drivers. Let me know what you think. Thanks, Wolfram Wolfram Sang (4): of: make of_mutex public dt-bindings: i2c: mux: demux-pinctrl: add bindings i2c: mux: demux-pinctrl: add driver ARM: shmobile: r8a7790: rework dts to use i2c demuxer .../devicetree/bindings/i2c/i2c-demux-pinctrl.txt | 155 ++++++++++++ arch/arm/boot/dts/r8a7790-lager.dts | 141 +++++++---- drivers/i2c/muxes/Kconfig | 9 + drivers/i2c/muxes/Makefile | 2 + drivers/i2c/muxes/i2c-demux-pinctrl.c | 276 +++++++++++++++++++++ drivers/of/of_private.h | 1 - include/linux/of.h | 2 + 7 files changed, 532 insertions(+), 54 deletions(-) create mode 100644 Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt create mode 100644 drivers/i2c/muxes/i2c-demux-pinctrl.c -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
