On Tue, Mar 12, 2013 at 03:51:08PM +0100, Jean Delvare wrote:
> Most LM75-compatible chips can either sample much faster or with a
> much better resolution than the original LM75 chip. So far the lm75
> driver did not let the user take benefit of these improvements. Do it
> now.
>
> I decided to almost always configure the chip to use the best
> resolution possible, which also means the longest sample time. The
> only chips for which I didn't are the DS75, DS1775 and STDS75, because
> they are really too slow in 12-bit mode (1.2 to 1.5 second worst case)
> so I went for 11-bit mode as a more reasonable tradeoff. This choice is
> dictated by the fact that the hwmon subsystem is meant for system
> monitoring, it has never been supposed to be ultra-fast, and as a
> matter of fact we do cache the sampled values in almost all drivers.
>
> If anyone isn't pleased with these default settings, they can always
> introduce a platform data structure or DT support for the lm75. That
> being said, it seems nobody ever complained that the driver wouldn't
> refresh the value faster than every 1.5 second, and the change made
> it faster for all chips even in 12-bit mode, so I don't expect any
> complaint.
>
I have been using update-interval to make it configurable.
Good example is the LM90 driver.
> Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
Acked-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> Documentation/hwmon/lm75 | 7 ++++---
> drivers/hwmon/lm75.c | 42 ++++++++++++++++++++++++++++++++++++------
> 2 files changed, 40 insertions(+), 9 deletions(-)
>
> --- linux-3.9-rc2.orig/drivers/hwmon/lm75.c 2013-03-12 15:46:05.343493393 +0100
> +++ linux-3.9-rc2/drivers/hwmon/lm75.c 2013-03-12 15:46:06.388517515 +0100
> @@ -169,6 +169,7 @@ lm75_probe(struct i2c_client *client, co
> int status;
> u8 set_mask, clr_mask;
> int new;
> + enum lm75_type kind = id->driver_data;
>
> if (!i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
> @@ -187,30 +188,59 @@ lm75_probe(struct i2c_client *client, co
> set_mask = 0;
> clr_mask = LM75_SHUTDOWN; /* continuous conversions */
>
> - switch (id->driver_data) {
> + switch (kind) {
> case adt75:
> clr_mask |= 1 << 5; /* not one-shot mode */
> + data->resolution = 12;
> + data->sample_time = HZ / 8;
> break;
> case ds1775:
> case ds75:
> case stds75:
> - clr_mask |= 3 << 5; /* 9-bit mode */
> + clr_mask |= 3 << 5;
> + set_mask |= 2 << 5; /* 11-bit mode */
> + data->resolution = 11;
> + data->sample_time = HZ;
> + break;
> + case lm75:
> + case lm75a:
> + data->resolution = 9;
> + data->sample_time = HZ / 2;
> + break;
> + case max6625:
> + data->resolution = 9;
> + data->sample_time = HZ / 4;
> + break;
> + case max6626:
> + data->resolution = 12;
> + data->resolution_limits = 9;
> + data->sample_time = HZ / 4;
> + break;
> + case tcn75:
> + data->resolution = 9;
> + data->sample_time = HZ / 8;
> break;
> case mcp980x:
> + data->resolution_limits = 9;
> + /* fall through */
> case tmp100:
> case tmp101:
> + set_mask |= 3 << 5; /* 12-bit mode */
> + data->resolution = 12;
> + data->sample_time = HZ;
> + clr_mask |= 1 << 7; /* not one-shot mode */
> + break;
> case tmp105:
> case tmp175:
> case tmp275:
> case tmp75:
> - clr_mask |= 3 << 5; /* 9-bit mode */
> + set_mask |= 3 << 5; /* 12-bit mode */
> clr_mask |= 1 << 7; /* not one-shot mode */
> + data->resolution = 12;
> + data->sample_time = HZ / 2;
> break;
> }
>
> - data->resolution = 9;
> - data->sample_time = HZ + HZ / 2;
> -
> /* configure as specified */
> status = lm75_read_value(client, LM75_REG_CONF);
> if (status < 0) {
> --- linux-3.9-rc2.orig/Documentation/hwmon/lm75 2013-03-12 15:09:42.543176379 +0100
> +++ linux-3.9-rc2/Documentation/hwmon/lm75 2013-03-12 15:49:08.893730398 +0100
> @@ -67,7 +67,8 @@ the temperature falls below the Hysteres
> All temperatures are in degrees Celsius, and are guaranteed within a
> range of -55 to +125 degrees.
>
> -The LM75 only updates its values each 1.5 seconds; reading it more often
> +The driver caches the values for a period varying between 1 second for the
> +slowest chips and 125 ms for the fastest chips; reading it more often
> will do no harm, but will return 'old' values.
>
> The original LM75 was typically used in combination with LM78-like chips
> @@ -78,8 +79,8 @@ The LM75 is essentially an industry stan
> LM75 clones not listed here, with or without various enhancements,
> that are supported. The clones are not detected by the driver, unless
> they reproduce the exact register tricks of the original LM75, and must
> -therefore be instantiated explicitly. The specific enhancements (such as
> -higher resolution) are not currently supported by the driver.
> +therefore be instantiated explicitly. Higher resolution up to 12-bit
> +is supported by this driver, other specific enhancements are not.
>
> The LM77 is not supported, contrary to what we pretended for a long time.
> Both chips are simply not compatible, value encoding differs.
>
> --
> Jean Delvare
>
> _______________________________________________
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> lm-sensors@xxxxxxxxxxxxxx
> http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
>
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