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Message-ID: <d2c6ce2b-de82-4ef8-a811-5379ee0179ec@roeck-us.net>
Date: Sat, 17 Jun 2023 08:51:11 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: JuenKit Yip <JuenKit_Yip@...mail.com>
Cc: jdelvare@...e.com, linux-hwmon@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/6] hwmon: (sht3x)remove blocking_io property
On Sat, Jun 17, 2023 at 12:00:13AM +0800, JuenKit Yip wrote:
> Due to no support on clock-strench, blocking mode was removed and
> now single-shot mode only uses non-blocking mode.
>
> Signed-off-by: JuenKit Yip <JuenKit_Yip@...mail.com>
Applied to hwmon-next.
Thanks,
Guenter
> ---
> Documentation/hwmon/sht3x.rst | 14 ++++++--------
> drivers/hwmon/sht3x.c | 33 +++++++++++----------------------
> 2 files changed, 17 insertions(+), 30 deletions(-)
>
> diff --git a/Documentation/hwmon/sht3x.rst b/Documentation/hwmon/sht3x.rst
> index 31fd36b14..be70e2543 100644
> --- a/Documentation/hwmon/sht3x.rst
> +++ b/Documentation/hwmon/sht3x.rst
> @@ -28,16 +28,14 @@ The device communicates with the I2C protocol. Sensors can have the I2C
> addresses 0x44 or 0x45, depending on the wiring. See
> Documentation/i2c/instantiating-devices.rst for methods to instantiate the device.
>
> -There are two options configurable by means of sht3x_data:
> -
> -1. blocking (pull the I2C clock line down while performing the measurement) or
> - non-blocking mode. Blocking mode will guarantee the fastest result but
> - the I2C bus will be busy during that time. By default, non-blocking mode
> - is used. Make sure clock-stretching works properly on your device if you
> - want to use blocking mode.
> -2. high or low accuracy. High accuracy is used by default and using it is
> +There is only one option configurable by means of sht3x_data:
> +
> + high or low accuracy. High accuracy is used by default and using it is
> strongly recommended.
>
> +Even if sht3x sensor supports clock-strech(blocking mode) and non-strench
> +(non-blocking mode) in single-shot mode, this driver only supports the latter.
> +
> The sht3x sensor supports a single shot mode as well as 5 periodic measure
> modes, which can be controlled with the update_interval sysfs interface.
> The allowed update_interval in milliseconds are as follows:
> diff --git a/drivers/hwmon/sht3x.c b/drivers/hwmon/sht3x.c
> index 580704d93..bbe556f44 100644
> --- a/drivers/hwmon/sht3x.c
> +++ b/drivers/hwmon/sht3x.c
> @@ -22,12 +22,10 @@
> #include <linux/jiffies.h>
>
> /* commands (high precision mode) */
> -static const unsigned char sht3x_cmd_measure_blocking_hpm[] = { 0x2c, 0x06 };
> -static const unsigned char sht3x_cmd_measure_nonblocking_hpm[] = { 0x24, 0x00 };
> +static const unsigned char sht3x_cmd_measure_single_hpm[] = { 0x24, 0x00 };
>
> /* commands (low power mode) */
> -static const unsigned char sht3x_cmd_measure_blocking_lpm[] = { 0x2c, 0x10 };
> -static const unsigned char sht3x_cmd_measure_nonblocking_lpm[] = { 0x24, 0x16 };
> +static const unsigned char sht3x_cmd_measure_single_lpm[] = { 0x24, 0x16 };
>
> /* commands for periodic mode */
> static const unsigned char sht3x_cmd_measure_periodic_mode[] = { 0xe0, 0x00 };
> @@ -41,9 +39,9 @@ static const unsigned char sht3x_cmd_heater_off[] = { 0x30, 0x66 };
> static const unsigned char sht3x_cmd_read_status_reg[] = { 0xf3, 0x2d };
> static const unsigned char sht3x_cmd_clear_status_reg[] = { 0x30, 0x41 };
>
> -/* delays for non-blocking i2c commands, both in us */
> -#define SHT3X_NONBLOCKING_WAIT_TIME_HPM 15000
> -#define SHT3X_NONBLOCKING_WAIT_TIME_LPM 4000
> +/* delays for single-shot mode i2c commands, both in us */
> +#define SHT3X_SINGLE_WAIT_TIME_HPM 15000
> +#define SHT3X_SINGLE_WAIT_TIME_LPM 4000
>
> #define SHT3X_WORD_LEN 2
> #define SHT3X_CMD_LENGTH 2
> @@ -134,7 +132,6 @@ struct sht3x_data {
> const unsigned char *command;
> u32 wait_time; /* in us*/
> unsigned long last_update; /* last update in periodic mode*/
> - bool blocking_io;
> bool high_precision;
>
> /*
> @@ -432,26 +429,19 @@ static ssize_t humidity1_limit_store(struct device *dev,
> static void sht3x_select_command(struct sht3x_data *data)
> {
> /*
> - * In blocking mode (clock stretching mode) the I2C bus
> - * is blocked for other traffic, thus the call to i2c_master_recv()
> - * will wait until the data is ready. For non blocking mode, we
> - * have to wait ourselves.
> + * For single-shot mode, only non blocking mode is support,
> + * we have to wait ourselves for result.
> */
> if (data->mode > 0) {
> data->command = sht3x_cmd_measure_periodic_mode;
> data->wait_time = 0;
> - } else if (data->blocking_io) {
> - data->command = data->high_precision ?
> - sht3x_cmd_measure_blocking_hpm :
> - sht3x_cmd_measure_blocking_lpm;
> - data->wait_time = 0;
> } else {
> if (data->high_precision) {
> - data->command = sht3x_cmd_measure_nonblocking_hpm;
> - data->wait_time = SHT3X_NONBLOCKING_WAIT_TIME_HPM;
> + data->command = sht3x_cmd_measure_single_hpm;
> + data->wait_time = SHT3X_SINGLE_WAIT_TIME_HPM;
> } else {
> - data->command = sht3x_cmd_measure_nonblocking_lpm;
> - data->wait_time = SHT3X_NONBLOCKING_WAIT_TIME_LPM;
> + data->command = sht3x_cmd_measure_single_lpm;
> + data->wait_time = SHT3X_SINGLE_WAIT_TIME_LPM;
> }
> }
> }
> @@ -689,7 +679,6 @@ static int sht3x_probe(struct i2c_client *client)
> if (!data)
> return -ENOMEM;
>
> - data->blocking_io = false;
> data->high_precision = true;
> data->mode = 0;
> data->last_update = jiffies - msecs_to_jiffies(3000);
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