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    Subject[PATCH v4 4/4] hwmon: lm75: Handle broken device nodes gracefully
    Date
    There is a logical flaw in lm75_probe() function introduced in

    e97a45f1b460 ("hwmon: (lm75) Add OF device ID table")

    Note, that of_device_get_match_data() returns NULL when no match
    is found. This is the case when OF node exists but has unknown
    compatible line, while the module is still loaded via i2c
    detection.

    arch/powerpc/boot/dts/fsl/p2041rdb.dts:

    lm75b@48 {
    compatible = "nxp,lm75a";
    reg = <0x48>;
    };

    In this case, the sensor is mistakenly considered as ADT75 variant.

    Fixes: e97a45f1b460 ("hwmon: (lm75) Add OF device ID table")
    Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru>
    ---
    drivers/hwmon/lm75.c | 13 ++++++++++---
    1 file changed, 10 insertions(+), 3 deletions(-)

    diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
    index 3e4374aa2f99..cd2cda4f557a 100644
    --- a/drivers/hwmon/lm75.c
    +++ b/drivers/hwmon/lm75.c
    @@ -567,10 +567,17 @@ static int lm75_probe(struct i2c_client *client)
    int status, err;
    enum lm75_type kind;

    - if (client->dev.of_node)
    - kind = (enum lm75_type)of_device_get_match_data(&client->dev);
    - else
    + if (dev->of_node) {
    + const struct of_device_id *match =
    + of_match_device(dev->driver->of_match_table, dev);
    +
    + if (!match)
    + return -ENODEV;
    +
    + kind = (enum lm75_type)(match->data);
    + } else {
    kind = i2c_match_id(lm75_ids, client)->driver_data;
    + }

    if (!i2c_check_functionality(client->adapter,
    I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
    --
    2.26.2
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