This is a note to let you know that I've just added the patch titled
hwmon: HIH-6130: Support I2C bus drivers without I2C_FUNC_SMBUS_QUICK
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hwmon-hih-6130-support-i2c-bus-drivers-without-i2c_func_smbus_quick.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From efabcc2123f0ed47870033b8d6fc73b50d76d635 Mon Sep 17 00:00:00 2001
From: José Miguel Gonçalves <jose.goncalves@xxxxxxx>
Date: Wed, 11 Dec 2013 11:11:13 +0000
Subject: hwmon: HIH-6130: Support I2C bus drivers without I2C_FUNC_SMBUS_QUICK
From: José Miguel Gonçalves <jose.goncalves@xxxxxxx>
commit efabcc2123f0ed47870033b8d6fc73b50d76d635 upstream.
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@xxxxxxx>
[Guenter Roeck: Simplified complexity of write_length initialization]
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/hwmon/hih6130.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
--- 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(s
*/
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_clie
goto fail_remove_sysfs;
}
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK))
+ hih6130->write_length = 1;
+
return 0;
fail_remove_sysfs:
Patches currently in stable-queue which might be from jose.goncalves@xxxxxxx are
queue-3.12/hwmon-hih-6130-support-i2c-bus-drivers-without-i2c_func_smbus_quick.patch
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