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hwmon: (tmp102) Improve handling of initial read delay

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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: Nishanth Menon <nm@ti.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Guenter Roeck 2016-06-19 20:34:57 -07:00
parent 589f707c72
commit 3d8f7a89a1
1 changed files with 30 additions and 14 deletions
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44
drivers/hwmon/tmp102.c
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@ -13,6 +13,7 @@
* GNU General Public License for more details. * GNU General Public License for more details.
*/ */
#include <linux/delay.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/slab.h> #include <linux/slab.h>
@ -46,13 +47,16 @@
#define TMP102_TLOW_REG 0x02 #define TMP102_TLOW_REG 0x02
#define TMP102_THIGH_REG 0x03 #define TMP102_THIGH_REG 0x03
#define CONVERSION_TIME_MS 35 /* in milli-seconds */
struct tmp102 { struct tmp102 {
struct i2c_client *client; struct i2c_client *client;
struct mutex lock; struct mutex lock;
u16 config_orig; u16 config_orig;
unsigned long last_update; unsigned long last_update;
unsigned long ready_time;
bool valid;
int temp[3]; int temp[3];
bool first_time;
}; };
/* convert left adjusted 13-bit TMP102 register value to milliCelsius */ /* convert left adjusted 13-bit TMP102 register value to milliCelsius */
@ -73,13 +77,14 @@ static const u8 tmp102_reg[] = {
TMP102_THIGH_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 tmp102 *tmp102 = dev_get_drvdata(dev);
struct i2c_client *client = tmp102->client; struct i2c_client *client = tmp102->client;
mutex_lock(&tmp102->lock); 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; int i;
for (i = 0; i < ARRAY_SIZE(tmp102->temp); ++i) { for (i = 0; i < ARRAY_SIZE(tmp102->temp); ++i) {
int status = i2c_smbus_read_word_swapped(client, 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->temp[i] = tmp102_reg_to_mC(status);
} }
tmp102->last_update = jiffies; tmp102->last_update = jiffies;
tmp102->first_time = false; tmp102->valid = true;
} }
mutex_unlock(&tmp102->lock); mutex_unlock(&tmp102->lock);
return tmp102;
} }
static int tmp102_read_temp(void *dev, int *temp) 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 (time_before(jiffies, tmp102->ready_time)) {
if (tmp102->first_time) {
dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__); dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__);
return -EAGAIN; return -EAGAIN;
} }
tmp102_update_device(dev);
*temp = tmp102->temp[0]; *temp = tmp102->temp[0];
return 0; return 0;
@ -114,12 +119,13 @@ static ssize_t tmp102_show_temp(struct device *dev,
char *buf) char *buf)
{ {
struct sensor_device_attribute *sda = to_sensor_dev_attr(attr); 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 (time_before(jiffies, tmp102->ready_time))
if (tmp102->first_time)
return -EAGAIN; return -EAGAIN;
tmp102_update_device(dev);
return sprintf(buf, "%d\n", tmp102->temp[sda->index]); 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"); dev_err(dev, "config settings did not stick\n");
return -ENODEV; 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); 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, hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
tmp102, tmp102,
tmp102_groups); tmp102_groups);
@ -261,12 +274,15 @@ static int tmp102_suspend(struct device *dev)
static int tmp102_resume(struct device *dev) static int tmp102_resume(struct device *dev)
{ {
struct i2c_client *client = to_i2c_client(dev); struct i2c_client *client = to_i2c_client(dev);
struct tmp102 *tmp102 = i2c_get_clientdata(client);
int config; int config;
config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG); config = i2c_smbus_read_word_swapped(client, TMP102_CONF_REG);
if (config < 0) if (config < 0)
return config; return config;
tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS);
config &= ~TMP102_CONF_SD; config &= ~TMP102_CONF_SD;
return i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, config); return i2c_smbus_write_word_swapped(client, TMP102_CONF_REG, config);
} }