From: Guenter Roeck <linux@roeck-us.net> To: Jean Delvare <jdelvare@suse.com> Cc: Nishanth Menon <nm@ti.com>, linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, Guenter Roeck <linux@roeck-us.net> Subject: [PATCH 3/5] hwmon: (tmp102) Improve handling of initial read delay Date: Thu, 23 Jun 2016 17:28:26 -0700 [thread overview] Message-ID: <1466728108-2512-3-git-send-email-linux@roeck-us.net> (raw) In-Reply-To: <1466728108-2512-1-git-send-email-linux@roeck-us.net> 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. Instead of returning -EAGAIN if data is not yet available, go to sleep for the remaining time. 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 <linux@roeck-us.net> --- drivers/hwmon/tmp102.c | 44 ++++++++++++++++++++++++++++---------------- 1 file changed, 28 insertions(+), 16 deletions(-) diff --git a/drivers/hwmon/tmp102.c b/drivers/hwmon/tmp102.c index 5bdf262e6a0e..615f9c176aaf 100644 --- a/drivers/hwmon/tmp102.c +++ b/drivers/hwmon/tmp102.c @@ -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 */ @@ -78,8 +82,16 @@ static struct tmp102 *tmp102_update_device(struct device *dev) struct tmp102 *tmp102 = dev_get_drvdata(dev); struct i2c_client *client = tmp102->client; + /* Is it too early to return a conversion ? */ + if (time_before(jiffies, tmp102->ready_time)) { + unsigned long sleeptime = tmp102->ready_time - jiffies; + + msleep(jiffies_to_msecs(sleeptime)); + } + 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, @@ -88,7 +100,7 @@ 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; @@ -98,12 +110,6 @@ static int tmp102_read_temp(void *dev, int *temp) { struct tmp102 *tmp102 = tmp102_update_device(dev); - /* Is it too early even to return a conversion? */ - if (tmp102->first_time) { - dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__); - return -EAGAIN; - } - *temp = tmp102->temp[0]; return 0; @@ -116,10 +122,6 @@ static ssize_t tmp102_show_temp(struct device *dev, struct sensor_device_attribute *sda = to_sensor_dev_attr(attr); struct tmp102 *tmp102 = tmp102_update_device(dev); - /* Is it too early even to return a read? */ - if (tmp102->first_time) - return -EAGAIN; - return sprintf(buf, "%d\n", tmp102->temp[sda->index]); } @@ -224,11 +226,18 @@ 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 +270,15 @@ 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
next prev parent reply other threads:[~2016-06-24 0:28 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-24 0:28 [PATCH 1/5] hwmon: (tmp102) Use devm_add_action to register cleanup function Guenter Roeck 2016-06-24 0:28 ` [PATCH 2/5] hwmon: (tmp102) Drop FSF address Guenter Roeck 2016-06-24 0:28 ` Guenter Roeck [this message] 2016-06-24 0:28 ` [PATCH 4/5] hwmon: (tmp102) Rework chip configuration Guenter Roeck 2016-06-24 0:28 ` [PATCH 5/5] hwmon: (tmp102) Convert to use regmap, and drop local cache Guenter Roeck 2016-06-24 14:13 ` [PATCH 1/5] hwmon: (tmp102) Use devm_add_action to register cleanup function Nishanth Menon 2016-06-24 14:30 ` Guenter Roeck 2016-06-24 14:54 ` Guenter Roeck 2016-06-24 15:23 ` Nishanth Menon 2016-06-24 15:31 ` Nishanth Menon 2016-06-24 16:36 ` Guenter Roeck 2016-06-24 18:02 ` Nishanth Menon 2016-06-24 18:18 ` Guenter Roeck 2016-06-24 18:21 ` Nishanth Menon 2016-06-25 1:24 ` Guenter Roeck
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