[rtc-linux] [PATCH] rtc: ds1307: ds3231 temperature s16 overflow

[rtc-linux] [PATCH] rtc: ds1307: ds3231 temperature s16 overflow

[Akinobu Mita]

From: Zhuang Yuyao <mlistz@gmail.com>

while retrieving temperature from ds3231, the result may be overflow
since s16 is too small for a multiplication with 250.

ie. if temp_buf[0] == 0x2d, the result (s16 temp) will be negative.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Zhuang Yuyao <mlistz@gmail.com>
Cc: Zhuang Yuyao <zhuangyy@syan.com.cn>
Cc: Michael Tatarinov <kukabu@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
 drivers/rtc/rtc-ds1307.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index cb0ffa8..90d1e5a 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -863,7 +863,7 @@ out:
  * A user-initiated temperature conversion is not started by this function,
  * so the temperature is updated once every 64 seconds.
  */
-static int ds3231_hwmon_read_temp(struct device *dev, s16 *mC)
+static int ds3231_hwmon_read_temp(struct device *dev, s32 *mC)
 {
 	struct ds1307 *ds1307 = dev_get_drvdata(dev);
 	u8 temp_buf[2];
@@ -892,7 +892,7 @@ static ssize_t ds3231_hwmon_show_temp(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	int ret;
-	s16 temp;
+	s32 temp;
 
 	ret = ds3231_hwmon_read_temp(dev, &temp);
 	if (ret)
-- 
2.5.0

-- 
-- 
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
--- 
You received this message because you are subscribed to the Google Groups "rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[rtc-linux] Re: [PATCH] rtc: ds1307: ds3231 temperature s16 overflow

[Michael Tatarinov]

Hello

Thanks!
I haven't tested the patch yet but I already have a question. What
about s16 in ds3231_hwmon_show_temp()?


2016-04-18 4:21 GMT+04:00, Akinobu Mita <akinobu.mita@gmail.com>:
> From: Zhuang Yuyao <mlistz@gmail.com>
>
> while retrieving temperature from ds3231, the result may be overflow
> since s16 is too small for a multiplication with 250.
>
> ie. if temp_buf[0] == 0x2d, the result (s16 temp) will be negative.
>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: Zhuang Yuyao <mlistz@gmail.com>
> Cc: Zhuang Yuyao <zhuangyy@syan.com.cn>
> Cc: Michael Tatarinov <kukabu@gmail.com>
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---
>  drivers/rtc/rtc-ds1307.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> index cb0ffa8..90d1e5a 100644
> --- a/drivers/rtc/rtc-ds1307.c
> +++ b/drivers/rtc/rtc-ds1307.c
> @@ -863,7 +863,7 @@ out:
>   * A user-initiated temperature conversion is not started by this
> function,
>   * so the temperature is updated once every 64 seconds.
>   */
> -static int ds3231_hwmon_read_temp(struct device *dev, s16 *mC)
> +static int ds3231_hwmon_read_temp(struct device *dev, s32 *mC)
>  {
>  	struct ds1307 *ds1307 = dev_get_drvdata(dev);
>  	u8 temp_buf[2];
> @@ -892,7 +892,7 @@ static ssize_t ds3231_hwmon_show_temp(struct device
> *dev,
>  				struct device_attribute *attr, char *buf)
>  {
>  	int ret;
> -	s16 temp;
> +	s32 temp;
>
>  	ret = ds3231_hwmon_read_temp(dev, &temp);
>  	if (ret)
> --
> 2.5.0
>
>

-- 
-- 
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
--- 
You received this message because you are subscribed to the Google Groups "rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[rtc-linux] Re: [PATCH] rtc: ds1307: ds3231 temperature s16 overflow

[Michael Tatarinov]

sorry, I realized my mistake

2016-04-18 8:33 GMT+04:00, Michael Tatarinov <kukabu@gmail.com>:
> Hello
>
> Thanks!
> I haven't tested the patch yet but I already have a question. What
> about s16 in ds3231_hwmon_show_temp()?
>
>
> 2016-04-18 4:21 GMT+04:00, Akinobu Mita <akinobu.mita@gmail.com>:
>> From: Zhuang Yuyao <mlistz@gmail.com>
>>
>> while retrieving temperature from ds3231, the result may be overflow
>> since s16 is too small for a multiplication with 250.
>>
>> ie. if temp_buf[0] == 0x2d, the result (s16 temp) will be negative.
>>
>> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
>> Cc: Zhuang Yuyao <mlistz@gmail.com>
>> Cc: Zhuang Yuyao <zhuangyy@syan.com.cn>
>> Cc: Michael Tatarinov <kukabu@gmail.com>
>> Cc: Alessandro Zummo <a.zummo@towertech.it>
>> Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
>> ---
>>  drivers/rtc/rtc-ds1307.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
>> index cb0ffa8..90d1e5a 100644
>> --- a/drivers/rtc/rtc-ds1307.c
>> +++ b/drivers/rtc/rtc-ds1307.c
>> @@ -863,7 +863,7 @@ out:
>>   * A user-initiated temperature conversion is not started by this
>> function,
>>   * so the temperature is updated once every 64 seconds.
>>   */
>> -static int ds3231_hwmon_read_temp(struct device *dev, s16 *mC)
>> +static int ds3231_hwmon_read_temp(struct device *dev, s32 *mC)
>>  {
>>  	struct ds1307 *ds1307 = dev_get_drvdata(dev);
>>  	u8 temp_buf[2];
>> @@ -892,7 +892,7 @@ static ssize_t ds3231_hwmon_show_temp(struct device
>> *dev,
>>  				struct device_attribute *attr, char *buf)
>>  {
>>  	int ret;
>> -	s16 temp;
>> +	s32 temp;
>>
>>  	ret = ds3231_hwmon_read_temp(dev, &temp);
>>  	if (ret)
>> --
>> 2.5.0
>>
>>
>

-- 
-- 
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
--- 
You received this message because you are subscribed to the Google Groups "rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[rtc-linux] Re: [PATCH] rtc: ds1307: ds3231 temperature s16 overflow

[Michael Tatarinov]

Thanks.

I'm testing the patch, it workins as expected.

$ cat /sys/devices/platform/soc/20804000.i2c/i2c-1/1-0068/hwmon/hwmon1/temp1_input
33000

2016-04-18 4:21 GMT+04:00, Akinobu Mita <akinobu.mita@gmail.com>:
> From: Zhuang Yuyao <mlistz@gmail.com>
>
> while retrieving temperature from ds3231, the result may be overflow
> since s16 is too small for a multiplication with 250.
>
> ie. if temp_buf[0] == 0x2d, the result (s16 temp) will be negative.

-- 
-- 
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
--- 
You received this message because you are subscribed to the Google Groups "rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[rtc-linux] Re: [PATCH] rtc: ds1307: ds3231 temperature s16 overflow

[Akinobu Mita]

2016-04-18 19:24 GMT+09:00 Michael Tatarinov <kukabu@gmail.com>:
> Thanks.
>
> I'm testing the patch, it workins as expected.
>
> $ cat /sys/devices/platform/soc/20804000.i2c/i2c-1/1-0068/hwmon/hwmon1/temp1_input
> 33000

Thanks for testing!

Can I put your Tested-by tag in this patch?

-- 
-- 
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
--- 
You received this message because you are subscribed to the Google Groups "rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[rtc-linux] Re: [PATCH] rtc: ds1307: ds3231 temperature s16 overflow

[Michael Tatarinov]

2016-04-18 17:05 GMT+04:00, Akinobu Mita <akinobu.mita@gmail.com>:
> 2016-04-18 19:24 GMT+09:00 Michael Tatarinov <kukabu@gmail.com>:
>> Thanks.
>>
>> I'm testing the patch, it workins as expected.
>>
>> $ cat
>> /sys/devices/platform/soc/20804000.i2c/i2c-1/1-0068/hwmon/hwmon1/temp1_input
>> 33000
>
> Thanks for testing!

Thanks for original patch and fix. :)

> Can I put your Tested-by tag in this patch?

Yes.

-- 
-- 
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
--- 
You received this message because you are subscribed to the Google Groups "rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[rtc-linux] Re: [PATCH] rtc: ds1307: ds3231 temperature s16 overflow

[Alexandre Belloni]

On 18/04/2016 at 09:21:42 +0900, Akinobu Mita wrote :
> From: Zhuang Yuyao <mlistz@gmail.com>
> 
> while retrieving temperature from ds3231, the result may be overflow
> since s16 is too small for a multiplication with 250.
> 
> ie. if temp_buf[0] == 0x2d, the result (s16 temp) will be negative.
> 
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: Zhuang Yuyao <mlistz@gmail.com>
> Cc: Zhuang Yuyao <zhuangyy@syan.com.cn>
> Cc: Michael Tatarinov <kukabu@gmail.com>
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---
>  drivers/rtc/rtc-ds1307.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
Applied, thanks.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

-- 
-- 
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
--- 
You received this message because you are subscribed to the Google Groups "rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.