When a driver with a ->detect callback (such as lm75) is loaded, the i2c core performs I2C transactions on the bus to all the addresses listed in that driver's address_list. This kind of probing wastes time and as Documentation/i2c/instantiating-devices.rst says, this method is not recommended and it is instead advised to list all devices in the devicetree. However, even if all the devices are listed in the devicetree, there is currently no way to prevent the core from attempting auto detection short of patching controller drivers to not pass the I2C_CLASS* bits in adap->class. The latter is not always possible since generic drivers like i2c-gpio set these bits. To avoid this unnecessary probing and reduce boot time, this series adds a property to the devicetree and support in the I2C core to allow this feature to be disabled. Cc: linux-i2c@xxxxxxxxxxxxxxx Cc: devicetree@xxxxxxxxxxxxxxx Cc: krzk+dt@xxxxxxxxxx Cc: robh+dt@xxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Vincent Whitchurch (2): i2c: add binding to prevent device detection i2c: core: support no-detect property Documentation/devicetree/bindings/i2c/i2c.txt | 4 ++++ drivers/i2c/i2c-core-base.c | 8 +++++++- include/linux/i2c.h | 1 + 3 files changed, 12 insertions(+), 1 deletion(-) -- 2.34.1
