On 9/4/20 1:33 AM, Lars Povlsen wrote: > > Guenter Roeck writes: > >> On 9/3/20 6:47 AM, Lars Povlsen wrote: >>> If the temperature is read before the internal calibration is >>> completed, the driver returns -EIO. Instead it should return -EAGAIN >>> to encourage repeating the operation. >>> >>> Signed-off-by: Lars Povlsen <lars.povlsen@xxxxxxxxxxxxx> >>> --- >>> drivers/hwmon/sparx5-temp.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/hwmon/sparx5-temp.c b/drivers/hwmon/sparx5-temp.c >>> index 1a2b1026b026..98be48e3a22a 100644 >>> --- a/drivers/hwmon/sparx5-temp.c >>> +++ b/drivers/hwmon/sparx5-temp.c >>> @@ -56,7 +56,7 @@ static int s5_read(struct device *dev, enum hwmon_sensor_types type, >>> case hwmon_temp_input: >>> stat = readl_relaxed(hwmon->base + TEMP_STAT); >>> if (!(stat & TEMP_STAT_VALID)) >>> - return -EIO; >>> + return -EAGAIN; >> >> The problem is that this may result in a hard loop and effectively hang the system, >> or at least the calling process. It may be better to return -ENODATA in this situation. >> > > Guenther, > > Thank you for your response. > > The motivation for the patch was as I tried to use thermal support to > control a fan, and I noticed an initial quip from > thermal_core.c:update_temperature() - it will throw a dev_warn() for > anything else than an "EAGAIN". The EAGAIN also seems to be used by > several other hwmon drivers in similar situations. > > The bottom line is that I would like to get rid of the warning > message. Changing the error code to ENODATA does not fix what I am > trying to accomplish. > Sigh. I know that -EAGAIN is used, but it has its own problems - userspace is inclined to retry directly, causing hard loops. Ok, lets go with -EAGAIN then. Can't be helped. I'll apply your patch. Guenter > Do you have any suggestions on how to achieve the objective? > > Sincerely, > > ---Lars > >> Guenter >> >>> value = stat & TEMP_STAT_TEMP; >>> /* >>> * From register documentation: >>> -- >>> 2.27.0 >>> >
