[PATCH v4 4/4] hwmon: lm75: Handle broken device nodes gracefully

[Matwey V. Kornilov]

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 <mat...@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