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    Subject[PATCH 4.19 64/90] hwmon: (core) add thermal sensors only if dev->of_node is present
    Date
    [ Upstream commit c41dd48e21fae3e55b3670ccf2eb562fc1f6a67d ]

    Drivers may register to hwmon and request for also registering
    with the thermal subsystem (HWMON_C_REGISTER_TZ). However,
    some of these driver, e.g. marvell phy, may be probed from
    Device Tree or being dynamically allocated, and in the later
    case, it will not have a dev->of_node entry.

    Registering with hwmon without the dev->of_node may result in
    different outcomes depending on the device tree, which may
    be a bit misleading. If the device tree blob has no 'thermal-zones'
    node, the *hwmon_device_register*() family functions are going
    to gracefully succeed, because of-thermal,
    *thermal_zone_of_sensor_register() return -ENODEV in this case,
    and the hwmon error path handles this error code as success to
    cover for the case where CONFIG_THERMAL_OF is not set.
    However, if the device tree blob has the 'thermal-zones'
    entry, the *hwmon_device_register*() will always fail on callers
    with no dev->of_node, propagating -EINVAL.

    If dev->of_node is not present, calling of-thermal does not
    make sense. For this reason, this patch checks first if the
    device has a of_node before going over the process of registering
    with the thermal subsystem of-thermal interface. And in this case,
    when a caller of *hwmon_device_register*() with HWMON_C_REGISTER_TZ
    and no dev->of_node will still register with hwmon, but not with
    the thermal subsystem. If all the hwmon part bits are in place,
    the registration will succeed.

    Fixes: d560168b5d0f ("hwmon: (core) New hwmon registration API")
    Cc: Jean Delvare <jdelvare@suse.com>
    Cc: Guenter Roeck <linux@roeck-us.net>
    Cc: linux-hwmon@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: Eduardo Valentin <eduval@amazon.com>
    Signed-off-by: Guenter Roeck <linux@roeck-us.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/hwmon/hwmon.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
    index fcdbac4a56e3..6b3559f58b67 100644
    --- a/drivers/hwmon/hwmon.c
    +++ b/drivers/hwmon/hwmon.c
    @@ -619,7 +619,7 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
    if (err)
    goto free_hwmon;

    - if (dev && chip && chip->ops->read &&
    + if (dev && dev->of_node && chip && chip->ops->read &&
    chip->info[0]->type == hwmon_chip &&
    (chip->info[0]->config[0] & HWMON_C_REGISTER_TZ)) {
    const struct hwmon_channel_info **info = chip->info;
    --
    2.20.1


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