Messages in this thread |  | | Date | Wed, 12 Jul 2017 00:03:02 +0200 | From | Tom Levens <> | Subject | Re: [v3,1/3] hwmon: ltc2990: refactor value conversion |
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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 */ > >
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