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Commit 3d8f7a89 authored by Guenter Roeck's avatar Guenter Roeck
Browse files

hwmon: (tmp102) Improve handling of initial read delay 



If the chip was in shutdown mode when the driver was loaded, the first
conversion is ready no more than 35 milli-seconds after the chip was
taken out of shutdown. The driver delay was so far set to 333 ms (HZ / 3),
which is much higher than the maximum time needed by the chip.
Reduce the time to 35 milli-seconds.

Introduce a 'valid' flag to ensure that sensor data is actually read
even if requested less than 333 ms after the driver was loaded.

Acked-by: default avatarNishanth Menon <nm@ti.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 589f707c

drivers/hwmon/tmp102.c

+30 −14
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
 * GNU General Public License for more details.

 */



#include <linux/delay.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/slab.h>
@@ -46,13 +47,16 @@ 
#define	TMP102_TLOW_REG			0x02

#define	TMP102_THIGH_REG		0x03



#define CONVERSION_TIME_MS		35	/* in milli-seconds */



struct tmp102 {

	struct i2c_client *client;

	struct mutex lock;

	u16 config_orig;

	unsigned long last_update;

	unsigned long ready_time;

	bool valid;

	int temp[3];

	bool first_time;

};



/* convert left adjusted 13-bit TMP102 register value to milliCelsius */
@@ -73,13 +77,14 @@ static const u8 tmp102_reg[] = { 
	TMP102_THIGH_REG,

};



static struct tmp102 *tmp102_update_device(struct device *dev)

static void tmp102_update_device(struct device *dev)

{

	struct tmp102 *tmp102 = dev_get_drvdata(dev);

	struct i2c_client *client = tmp102->client;



	mutex_lock(&tmp102->lock);

	if (time_after(jiffies, tmp102->last_update + HZ / 3)) {

	if (!tmp102->valid ||

	    time_after(jiffies, tmp102->last_update + HZ / 3)) {

		int i;

		for (i = 0; i < ARRAY_SIZE(tmp102->temp); ++i) {

			int status = i2c_smbus_read_word_swapped(client,
@@ -88,22 +93,22 @@ static struct tmp102 *tmp102_update_device(struct device *dev) 
				tmp102->temp[i] = tmp102_reg_to_mC(status);

		}

		tmp102->last_update = jiffies;

		tmp102->first_time = false;

		tmp102->valid = true;

	}

	mutex_unlock(&tmp102->lock);

	return tmp102;

}



static int tmp102_read_temp(void *dev, int *temp)

{

	struct tmp102 *tmp102 = tmp102_update_device(dev);

	struct tmp102 *tmp102 = dev_get_drvdata(dev);



	/* Is it too early even to return a conversion? */

	if (tmp102->first_time) {

	if (time_before(jiffies, tmp102->ready_time)) {

		dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__);

		return -EAGAIN;

	}



	tmp102_update_device(dev);



	*temp = tmp102->temp[0];



	return 0;
@@ -114,12 +119,13 @@ static ssize_t tmp102_show_temp(struct device *dev, 
				char *buf)

{

	struct sensor_device_attribute *sda = to_sensor_dev_attr(attr);

	struct tmp102 *tmp102 = tmp102_update_device(dev);

	struct tmp102 *tmp102 = dev_get_drvdata(dev);



	/* Is it too early even to return a read? */

	if (tmp102->first_time)

	if (time_before(jiffies, tmp102->ready_time))

		return -EAGAIN;



	tmp102_update_device(dev);



	return sprintf(buf, "%d\n", tmp102->temp[sda->index]);

}
@@ -224,11 +230,18 @@ static int tmp102_probe(struct i2c_client *client, 
		dev_err(dev, "config settings did not stick\n");

		return -ENODEV;

	}

	tmp102->last_update = jiffies;

	/* Mark that we are not ready with data until conversion is complete */

	tmp102->first_time = true;



	mutex_init(&tmp102->lock);



	tmp102->ready_time = jiffies;

	if (tmp102->config_orig & TMP102_CONF_SD) {

		/*

		 * Mark that we are not ready with data until the first

		 * conversion is complete

		 */

		tmp102->ready_time += msecs_to_jiffies(CONVERSION_TIME_MS);

	}



	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,

							   tmp102,

							   tmp102_groups);
@@ -261,12 +274,15 @@ static int tmp102_suspend(struct device *dev) 
static int tmp102_resume(struct device *dev)

{

	struct i2c_client *client = to_i2c_client(dev);

	struct tmp102 *tmp102 = i2c_get_clientdata(client);

	int config;



	config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);

	if (config < 0)

		return config;



	tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS);



	config &= ~TMP102_CONF_SD;

	return i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, config);

}