On 2/29/24 14:34, Subhajit Ghosh wrote:
On 29/2/24 03:57, Andy Shevchenko wrote:
On Wed, Feb 28, 2024 at 03:08:56PM +0200, Matti Vaittinen wrote:
On 2/28/24 14:24, Subhajit Ghosh wrote:
...
+ ret = iio_gts_find_new_gain_by_old_gain_time(&data->gts, gain_old,
+ intg_old, val2, &gain_new);
You don't use the 'ret' here, so maybe for the clarity, not assign it.
Or, maybe you wan't to try to squeeze out few cycles for succesful
case and
check the ret for '0' - in which case you should be able to omit the
check
right below as well as the call to iio_find_closest_gain_low(). OTOH,
this
is likely not a "hot path" so I don't care too much about the extra
call if
you think code is clearer this way.
+ if (gain_new < 0) {
+ dev_err_ratelimited(dev, "Unsupported gain with time\n");
+ return gain_new;
+ }
What is the difference between negative response from the function
itself and
similar in gain_new?
-ve response form the function is an error condition.
-ve value in gain_new means - no valid gains could be computed.
In case of error conditions from the function, the gain_new is also set
to -1.
My use case is valid hardware gain so I went for checking only gain_new.
Matti will be the best person to answer on this.
I now rely on the kerneldoc for the
iio_gts_find_new_gain_by_old_gain_time() as it seems reasonable to me:
* Return: 0 if an exactly matching supported new gain was found. When a
* non-zero value is returned, the @new_gain will be set to a negative or
* positive value. The negative value means that no gain could be computed.
* Positive value will be the "best possible new gain there could be". There
* can be two reasons why finding the "best possible" new gain is not deemed
* successful. 1) This new value cannot be supported by the hardware. 2)
The new
* gain required to maintain the scale would not be an integer. In this case,
* the "best possible" new gain will be a floored optimal gain, which may or
* may not be supported by the hardware.
Eg, if ret is zero, there is no need to check validity of the gain_new
but it is guaranteed to be one of the supported gains.
Yours,
-- Matti
--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland
~~ When things go utterly wrong vim users can always type :help! ~~
