Hello Harald
Thanks for the review.
On 3/25/24 21:48, Harald Geyer wrote:
Hi George!
I'm torn on this:
Am Montag, dem 25.03.2024 um 19:54 +0300 schrieb George Stark:
Protocol parsing errors could happen due to several reasons like
noise
environment, heavy load on system etc. If to poll the sensor
frequently
and/or for a long period kernel log will become polluted with error
messages if their log level is err (i.e. on by default).
Yes, these error are often recoverable. (As are many other HW errors,
that typically are logged. Eg USB bus resets due to EMI)
However they are still genuine errors of the HW.
Also some types
of those messages already have dbg level so use unified log level for
all such cases.
My take so far has been: Debug level messages are for debugging the
code (ie adding/testing support of new device variants etc). Users
aren't expected to know about or enable debug output. OTOH anything
actually going wrong is an error and should be logged as such.
The idea is, that these messages help users understand issues with
their HW (like too long cables, broken cables etc). But it is true,
that they will slowly accumulate in many real world scenarios without
anything being truly wrong.
I agree with you that it's very convenient to just take a look to dmesg
and see device connection problems at once. But unlike e.g. usb user has
to actually start reading sensor to perform communication and read
errors will be propagated to the userspace and could be noticed \
handled.
Anyway I believe we should use uniform approach for read errors -
currently in the driver there're already dbg messages:
"lost synchronisation at edge %d\n"
"invalid checksum\n"
I changed log level from err to dbg for the messages:
"Only %d signal edges detected\n"
"Don't know how to decode data: %d %d %d %d\n"
They all are from a single callback and say the same thing -
communication problem.
If we make all those messages as errors it'd be great to have mechanism
to disable them e.g. thru module parameter or somehow without rebuilding
kernel. Those errors can be bypassed by increasing read rate.
I don't consider the dmesg buffer being rotated after a month or two a
bug. But I suppose this is a corner case. I'll happily accept whatever
Jonathan thinks is reasonable.
Best regards,
Harald
Signed-off-by: George Stark <gnstark@xxxxxxxxxxxxxxxxx>
---
I use DHT22 sensor with Raspberry Pi Zero W as a simple home meteo
station.
Even if to poll the sensor once per tens of seconds after month or
two dmesg
may become full of useless parsing error messages. Anyway those
errors are caught
in the user software thru return values.
drivers/iio/humidity/dht11.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/humidity/dht11.c
b/drivers/iio/humidity/dht11.c
index c97e25448772..e2cbc442177b 100644
--- a/drivers/iio/humidity/dht11.c
+++ b/drivers/iio/humidity/dht11.c
@@ -156,7 +156,7 @@ static int dht11_decode(struct dht11 *dht11, int
offset)
dht11->temperature = temp_int * 1000;
dht11->humidity = hum_int * 1000;
} else {
- dev_err(dht11->dev,
+ dev_dbg(dht11->dev,
"Don't know how to decode data: %d %d %d
%d\n",
hum_int, hum_dec, temp_int, temp_dec);
return -EIO;
@@ -239,7 +239,7 @@ static int dht11_read_raw(struct iio_dev
*iio_dev,
#endif
if (ret == 0 && dht11->num_edges <
DHT11_EDGES_PER_READ - 1) {
- dev_err(dht11->dev, "Only %d signal edges
detected\n",
+ dev_dbg(dht11->dev, "Only %d signal edges
detected\n",
dht11->num_edges);
ret = -ETIMEDOUT;
}
--
2.25.1
--
Best regards
George
