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| author | José Miguel Gonçalves <jose.goncalves@inov.pt> | 2013-12-11 15:11:13 +0400 |
|---|---|---|
| committer | Guenter Roeck <linux@roeck-us.net> | 2013-12-12 01:37:30 +0400 |
| commit | efabcc2123f0ed47870033b8d6fc73b50d76d635 (patch) | |
| tree | 7cfd6a2641b7d7f5a616d5a4d346fbbb164eb59e /drivers/hwmon | |
| parent | 374b105797c3d4f29c685f3be535c35f5689b30e (diff) | |
| download | linux-efabcc2123f0ed47870033b8d6fc73b50d76d635.tar.xz | |
hwmon: HIH-6130: Support I2C bus drivers without I2C_FUNC_SMBUS_QUICK
Some I2C bus drivers do not allow zero-length data transfers which are
required to start a measurement with the HIH6130/1 sensor. Nevertheless,
we can overcome this limitation by writing a zero dummy byte. This byte
is ignored by the sensor and was verified to be working with the OMAP
I2C bus driver in a BeagleBone board.
Signed-off-by: José Miguel Gonçalves <jose.goncalves@inov.pt>
[Guenter Roeck: Simplified complexity of write_length initialization]
Cc: stable@vger.kernel.org # v3.10+
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Diffstat (limited to 'drivers/hwmon')
| -rw-r--r-- | drivers/hwmon/hih6130.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/hwmon/hih6130.c b/drivers/hwmon/hih6130.c index 2dc37c7c6947..7d68a08baaa8 100644 --- a/drivers/hwmon/hih6130.c +++ b/drivers/hwmon/hih6130.c @@ -43,6 +43,7 @@ * @last_update: time of last update (jiffies) * @temperature: cached temperature measurement value * @humidity: cached humidity measurement value + * @write_length: length for I2C measurement request */ struct hih6130 { struct device *hwmon_dev; @@ -51,6 +52,7 @@ struct hih6130 { unsigned long last_update; int temperature; int humidity; + size_t write_length; }; /** @@ -121,8 +123,15 @@ static int hih6130_update_measurements(struct i2c_client *client) */ if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) { - /* write to slave address, no data, to request a measurement */ - ret = i2c_master_send(client, tmp, 0); + /* + * Write to slave address to request a measurement. + * According with the datasheet it should be with no data, but + * for systems with I2C bus drivers that do not allow zero + * length packets we write one dummy byte to allow sensor + * measurements on them. + */ + tmp[0] = 0; + ret = i2c_master_send(client, tmp, hih6130->write_length); if (ret < 0) goto out; @@ -252,6 +261,9 @@ static int hih6130_probe(struct i2c_client *client, goto fail_remove_sysfs; } + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK)) + hih6130->write_length = 1; + return 0; fail_remove_sysfs: |