From af503716ac1444db61d80cb6d17cfe62929c21df Mon Sep 17 00:00:00 2001 From: Javier Martinez Canillas Date: Sun, 3 Dec 2017 22:40:50 +0100 Subject: [PATCH] i2c: core: report OF style module alias for devices registered via OF The buses should honor the firmware interface used to register the device, but the I2C core reports a MODALIAS of the form i2c: even for I2C devices registered via OF. This means that user-space will never get an OF stype uevent MODALIAS even when the drivers modules contain aliases exported from both the I2C and OF device ID tables. For example, an Atmel maXTouch Touchscreen registered by a DT node with compatible "atmel,maxtouch" has the following module alias: $ cat /sys/class/i2c-adapter/i2c-8/8-004b/modalias i2c:maxtouch So udev won't be able to auto-load a module for an OF-only device driver. Many OF-only drivers duplicate the OF device ID table entries in an I2C ID table only has a workaround for how the I2C core reports the module alias. This patch changes the I2C core to report an OF related MODALIAS uevent if the device was registered via OF. So for the previous example, after this patch, the reported MODALIAS for the Atmel maXTouch will be the following: $ cat /sys/class/i2c-adapter/i2c-8/8-004b/modalias of:NtrackpadTCatmel,maxtouch NOTE: This patch may break out-of-tree drivers that were relying on this behavior, and only had an I2C device ID table even when the device was registered via OF. There are no remaining drivers in mainline that do this, but out-of-tree drivers have to be fixed and define a proper OF device ID table to have module auto-loading working. Signed-off-by: Javier Martinez Canillas Tested-by: Dmitry Mastykin Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-core-base.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 5a00bf443d06..edfc23e49630 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -124,6 +124,10 @@ static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env) struct i2c_client *client = to_i2c_client(dev); int rc; + rc = of_device_uevent_modalias(dev, env); + if (rc != -ENODEV) + return rc; + rc = acpi_device_uevent_modalias(dev, env); if (rc != -ENODEV) return rc; @@ -439,6 +443,10 @@ show_modalias(struct device *dev, struct device_attribute *attr, char *buf) struct i2c_client *client = to_i2c_client(dev); int len; + len = of_device_modalias(dev, buf, PAGE_SIZE); + if (len != -ENODEV) + return len; + len = acpi_device_modalias(dev, buf, PAGE_SIZE -1); if (len != -ENODEV) return len; -- GitLab