lkml.org 
[lkml]   [2017]   [Jul]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [v3,1/3] hwmon: ltc2990: refactor value conversion


On Sat, 8 Jul 2017, Guenter Roeck wrote:

> On Mon, Jul 03, 2017 at 06:28:58AM +0200, Tom Levens wrote:
>> Conversion from raw values to signed integers has been refactored using
>> bitops.h. This also fixes a bug where negative temperatures were
>> converted incorrectly.
>>
>
> Documentation/process/submitting-patches.rst, chapter 2: "Solve only one
> problem per patch.".
>
> I can understand the urge to merge two sets of changes here. However,
> that creates a problem for me: The fix should be applied to stable kernels,
> but not the refactoring.
>
> Please split the patch in two, one for the bug fix and one for the
> refactoring.

In reality the refactoring *is* the fix for this bug. I am not sure how to
to fix it simply without using the bitops macro. Of course, I could fix
only the temperature conversion in one patch and refactor the other two in
a separate one if you prefer?

Cheers,

> Thanks,
> Guenter
>
>> Signed-off-by: Tom Levens <tom.levens@cern.ch>
>> ---
>> drivers/hwmon/ltc2990.c | 18 ++++--------------
>> 1 file changed, 4 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/hwmon/ltc2990.c b/drivers/hwmon/ltc2990.c
>> index 8f8fe05..e320d21 100644
>> --- a/drivers/hwmon/ltc2990.c
>> +++ b/drivers/hwmon/ltc2990.c
>> @@ -11,6 +11,7 @@
>> * the chip's internal temperature and Vcc power supply voltage.
>> */
>>
>> +#include <linux/bitops.h>
>> #include <linux/err.h>
>> #include <linux/hwmon.h>
>> #include <linux/hwmon-sysfs.h>
>> @@ -34,15 +35,6 @@
>> #define LTC2990_CONTROL_MODE_CURRENT 0x06
>> #define LTC2990_CONTROL_MODE_VOLTAGE 0x07
>>
>> -/* convert raw register value to sign-extended integer in 16-bit range */
>> -static int ltc2990_voltage_to_int(int raw)
>> -{
>> - if (raw & BIT(14))
>> - return -(0x4000 - (raw & 0x3FFF)) << 2;
>> - else
>> - return (raw & 0x3FFF) << 2;
>> -}
>> -
>> /* Return the converted value from the given register in uV or mC */
>> static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
>> {
>> @@ -55,18 +47,16 @@ static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
>> switch (reg) {
>> case LTC2990_TINT_MSB:
>> /* internal temp, 0.0625 degrees/LSB, 13-bit */
>> - val = (val & 0x1FFF) << 3;
>> - *result = (val * 1000) >> 7;
>> + *result = sign_extend32(val, 12) * 1000 / 16;
>> break;
>> case LTC2990_V1_MSB:
>> case LTC2990_V3_MSB:
>> /* Vx-Vy, 19.42uV/LSB. Depends on mode. */
>> - *result = ltc2990_voltage_to_int(val) * 1942 / (4 * 100);
>> + *result = sign_extend32(val, 14) * 1942 / 100;
>> break;
>> case LTC2990_VCC_MSB:
>> /* Vcc, 305.18μV/LSB, 2.5V offset */
>> - *result = (ltc2990_voltage_to_int(val) * 30518 /
>> - (4 * 100 * 1000)) + 2500;
>> + *result = sign_extend32(val, 14) * 30518 / (100 * 1000) + 2500;
>> break;
>> default:
>> return -EINVAL; /* won't happen, keep compiler happy */
>
>
\
 
 \ /
  Last update: 2017-07-12 00:03    [W:0.109 / U:0.236 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site