From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: From: Guenter Roeck To: Jean Delvare Cc: Nishanth Menon , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, Guenter Roeck Subject: [PATCH v3 1/3] hwmon: (tmp102) Improve handling of initial read delay Date: Wed, 29 Jun 2016 20:41:57 -0700 Message-Id: <1467258119-14071-1-git-send-email-linux@roeck-us.net> List-ID: 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. Signed-off-by: Guenter Roeck --- v3: Don't go to sleep if sensor readings are not available; instead, return -EAGAIN (matching previous behavior) tmp102_update_device() is now a void function. v2: No change Note: This series depends on the following two patches in -next. hwmon: (tmp102) Drop FSF address hwmon: (tmp102) Use devm_add_action to register cleanup function drivers/hwmon/tmp102.c | 44 ++++++++++++++++++++++++++++++-------------- 1 file changed, 30 insertions(+), 14 deletions(-) diff --git a/drivers/hwmon/tmp102.c b/drivers/hwmon/tmp102.c index 5bdf262e6a0e..fd4a4515692a 100644 --- a/drivers/hwmon/tmp102.c +++ b/drivers/hwmon/tmp102.c @@ -13,6 +13,7 @@ * GNU General Public License for more details. */ +#include #include #include #include @@ -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); } -- 2.5.0