Export this function in preparation for the fix in veml6030.c, where the
total gain can be used to ease the calculation of the processed value of
the IIO_LIGHT channel compared to acquiring the scale in NANO.
Suggested-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://patch.msgid.link/20250127-veml6030-scale-v3-1-4f32ba03df94@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Make available scale building more clear. This hurts the performance
quite a bit by looping throgh the scales many times instead of doing
everything in one loop. It however simplifies logic by:
- decoupling the gain and scale allocations & computations
- keeping the temporary 'per_time_gains' table inside the
per_time_scales computation function.
- separating building the 'all scales' table in own function and doing
it based on the already computed per-time scales.
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Tested-by: subhajit.ghosh@tweaklogic.com
Link: https://patch.msgid.link/Z1_rRXqdhxhL6wBw@mva-rohm
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This helper functions reduce the burden in the drivers that want to
fetch a gain and time selector for a given scale or a new optimal gain.
The former is currently achieved by calling
iio_gts_find_gain_sel_for_scale_using_time() for the current time
selector, and then iterating over the rest of time selectors if the
gain selector was not found.
The latter requires a combination of multiple iio-gts helpers to find
the new gain, look for an optimal gain if there was no exact match, and
set a minimum gain if the optimal gain is not in the range of available
gains.
Provide simpler workflows by means of functions that address common
patterns in the users of the iio-gts helpers.
Acked-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/20241230-veml3235_scale-v3-1-48a5795e2f64@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
In iio_gts_build_avail_time_table(), it is checked that gts->num_itime is
non-zero, but gts->num_itime is not checked in gain_to_scaletables(). The
variable time_idx is initialized as gts->num_itime - 1. This implies that
time_idx might initially be set to -1 (0 - 1 = -1). Consequently, using
while (time_idx--) could lead to an infinite loop.
Cc: stable@vger.kernel.org # v6.6+
Fixes: 38416c28e1 ("iio: light: Add gain-time-scale helpers")
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://patch.msgid.link/20241031014626.2313077-1-quzicheng@huawei.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Initialize the variable ret at the time of declaration to prevent it from
being returned without a defined value. Fixes smatch warning:
drivers/iio/industrialio-gts-helper.c:256 gain_to_scaletables() error:
uninitialized symbol 'ret'.
Cc: stable@vger.kernel.org # v6.6+
Fixes: 38416c28e1 ("iio: light: Add gain-time-scale helpers")
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://patch.msgid.link/20241031014505.2313035-1-quzicheng@huawei.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
If per_time_scales[i] or per_time_gains[i] kcalloc fails in the for loop
of iio_gts_build_avail_scale_table(), the err_free_out will fail to call
kfree() each time when i is reduced to 0, so all the per_time_scales[0]
and per_time_gains[0] will not be freed, which will cause memory leaks.
Fix it by checking if i >= 0.
Cc: stable@vger.kernel.org
Fixes: 38416c28e1 ("iio: light: Add gain-time-scale helpers")
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20241016012453.2013302-1-ruanjinjie@huawei.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The sorting in iio_gts_build_avail_time_table is not working as intended.
It could result in an out-of-bounds access when the time is zero.
Here are more details:
1. When the gts->itime_table[i].time_us is zero, e.g., the time
sequence is `3, 0, 1`, the inner for-loop will not terminate and do
out-of-bound writes. This is because once `times[j] > new`, the value
`new` will be added in the current position and the `times[j]` will be
moved to `j+1` position, which makes the if-condition always hold.
Meanwhile, idx will be added one, making the loop keep running without
termination and out-of-bound write.
2. If none of the gts->itime_table[i].time_us is zero, the elements
will just be copied without being sorted as described in the comment
"Sort times from all tables to one and remove duplicates".
For more details, please refer to
https://lore.kernel.org/all/6dd0d822-046c-4dd2-9532-79d7ab96ec05@gmail.com.
Reported-by: Chenyuan Yang <chenyuan0y@gmail.com>
Suggested-by: Matti Vaittinen <mazziesaccount@gmail.com>
Fixes: 38416c28e1 ("iio: light: Add gain-time-scale helpers")
Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
Co-developed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/d501ade8c1f7b202d34c6404eda423489cab1df5.1714480171.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The loop based 64bit division may run for a long time when dividend is a
lot bigger than the divider. Replace the division loop by the
div64_u64() which implementation may be significantly faster.
Tested-by: Subhajit Ghosh <subhajit.ghosh@tweaklogic.com>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Fixes: 38416c28e1 ("iio: light: Add gain-time-scale helpers")
Link: https://lore.kernel.org/r/Zcn-6e-0-nh2WcfU@drtxq0yyyyyyyyyyyyyby-3.rev.dnainternet.fi
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The IIO ABI mandates expressing integration times in seconds. The GTS
helper errorneously uses micro seconds in integration_times_available.
Fix this by converting the lists to IIO_VAL_INT_PLUS_MICRO.
Fixes: 38416c28e1 ("iio: light: Add gain-time-scale helpers")
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/eeacd192c259e885850b5a2dd8b776bccfc44fa8.1681722914.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Some light sensors can adjust both the HW-gain and integration time.
There are cases where adjusting the integration time has similar impact
to the scale of the reported values as gain setting has.
IIO users do typically expect to handle scale by a single writable 'scale'
entry. Driver should then adjust the gain/time accordingly.
It however is difficult for a driver to know whether it should change
gain or integration time to meet the requested scale. Usually it is
preferred to have longer integration time which usually improves
accuracy, but there may be use-cases where long measurement times can be
an issue. Thus it can be preferable to allow also changing the
integration time - but mitigate the scale impact by also changing the gain
underneath. Eg, if integration time change doubles the measured values,
the driver can reduce the HW-gain to half.
The theory of the computations of gain-time-scale is simple. However,
some people (undersigned) got that implemented wrong for more than once.
Add some gain-time-scale helpers in order to not dublicate errors in all
drivers needing these computations.
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/268d418e7cffcdaa2ece6738478bbc57692c213e.1680263956.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
