Messages in this thread Patch in this message | | | Subject | Re: hwmon: drivetemp: bogus values after wake up from suspend | From | Guenter Roeck <> | Date | Mon, 6 Apr 2020 18:41:42 -0700 |
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On 4/6/20 9:23 AM, Holger Hoffstätte wrote: > > I've been giving the drivetemp hwmon driver a try and am very happy > with it; works right away and - much to my surprise - doesn't wake up > HDDs that have gone to sleep. Nice! > > I did notice one tiny thing though: after waking up from suspend, my SSD > (Samsung 850 Pro) reports a few initial bogus values - suspiciously -128°, > which is definitely not the temperature in my office. While this is more > a cosmetic problem, it cramps my monitoring setup and leads to wrong graphs. > Can't have that! > > So I looked into the source and found that the values are (understandably) > passed on unfiltered/uncapped. Since it's unlikely any active device has > operating temperature below-zero, I figured the laziest way is to cap the > value to positive: > > diff -rup a/drivers/hwmon/drivetemp.c b/drivers/hwmon/drivetemp.c > --- a/drivers/hwmon/drivetemp.c 2020-04-02 08:02:32.000000000 +0200 > +++ b/drivers/hwmon/drivetemp.c 2020-04-06 18:13:04.892554087 +0200 > @@ -147,7 +147,7 @@ static LIST_HEAD(drivetemp_devlist); > #define INVALID_TEMP 0x80 > > #define temp_is_valid(temp) ((temp) != INVALID_TEMP) > -#define temp_from_sct(temp) (((s8)(temp)) * 1000) > +#define temp_from_sct(temp) (max(0, ((s8)(temp)) * 1000)) > > static inline bool ata_id_smart_supported(u16 *id) > { > > The assumption is of course *theoretically* wrong since some > equipment might indeed operate in negative C°. One way might be > to use the device's "low" operating point first, but then that > might not be available and we'd be back to capping to 0. > I'm open to other suggestions. :) >
Looking into the code, 0x80 or -128 indeed reflects an invalid temperature. Any chance you can apply the following to see if it helps ?
diff --git a/drivers/hwmon/drivetemp.c b/drivers/hwmon/drivetemp.c index 370d0c74eb01..c27239eb28cf 100644 --- a/drivers/hwmon/drivetemp.c +++ b/drivers/hwmon/drivetemp.c @@ -264,6 +264,8 @@ static int drivetemp_get_scttemp(struct drivetemp_data *st, u32 attr, long *val) return err; switch (attr) { case hwmon_temp_input: + if (!temp_is_valid(buf[SCT_STATUS_TEMP])) + return -ENODATA; *val = temp_from_sct(buf[SCT_STATUS_TEMP]); break; case hwmon_temp_lowest: I am not sure what the best error code would be - suggestions welcome.
Thanks, Guenter
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