On Tue, 5 Jan 2021 23:09:20 +0000 Jyoti Bhayana <jbhay...@google.com> wrote:
> Hi Jonathan, > > > So, sensor_max_range can effectively be exposed as a combination of > > scale and the *_raw_avail for a raw read (via the read_avail callback in > > IIO). > > We'll ignore the fact the interface assumes a single value (so I assume > > symmetric?) > > Based on the SCMI specification the sensor min range and max range are 64 > bits signed number. > > looks like IIO_AVAIL_RANGE can only take the following > types of data which all looks like 32 bit. IIO_VAL_FRACTIONAL > also takes two int type numbers. > How can I send 64 bit sensor range using this and read_avail callback? > > #define IIO_VAL_INT 1 > #define IIO_VAL_INT_PLUS_MICRO 2 > #define IIO_VAL_INT_PLUS_NANO 3 > #define IIO_VAL_INT_PLUS_MICRO_DB 4 > #define IIO_VAL_INT_MULTIPLE 5 > #define IIO_VAL_FRACTIONAL 10 > #define IIO_VAL_FRACTIONAL_LOG2 11 > #define IIO_VAL_CHAR 12 Hmm It is a bit unfortunate that SCMI decided to pretend that real sensor resolutions were greater than 32 bits. I doubt they will ever actually be any (as such accurate measurements are completely pointless) and they aren't anywhere near that today. Only way it might end up looking a bit like that would be result of a highly non linear sensor being shoved through an interface that pretends it isn't (goody). Having said that, specifications are what they are and we have to cope with that. There is no real problem with defining a new value type except for the fact that any legacy userspace won't necessarily expect to see values that large. Given we need the full 64 bits it would have to be something like IIO_VAL_INT_H32_L32 with the 64 bit values split up appropriately and put back together at time of formatting. Not particularly pretty but I'm not keep to put that much effort in to support something like this for one driver (so not interesting in changing that the read_raw_* interfaces) Jonathan > > > > Thanks, > Jyoti >
