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Commit eb13959e authored by Matti Vaittinen's avatar Matti Vaittinen Committed by Jonathan Cameron
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bu27034: ROHM BU27034ANUC correct lux calculation 

The ROHM BU27034NUC was cancelled and BU27034ANUC is replacing this
sensor. The lux computation based on the data from a BU27034ANUC is
different from the computation for the data from an old BU27034NUC.

Fix the lux computation.
Signed-off-by: default avatarMatti Vaittinen <mazziesaccount@gmail.com>
Link: https://patch.msgid.link/b7bea76b54b28eb354dc523771a0e0a8b6f26095.1720176341.git.mazziesaccount@gmail.comSigned-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent bb105981
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Showing with 31 additions and 126 deletions
drivers/iio/light/rohm-bu27034.c
View file @ eb13959e
......@@ -573,102 +573,21 @@ static int bu27034_set_scale(struct bu27034_data *data, int chan,
}
/*
* for (D1/D0 < 0.87):
* lx = 0.004521097 * D1 - 0.002663996 * D0 +
* 0.00012213 * D1 * D1 / D0
* for (D1/D0 < 1.5):
* lx = (0.001193 * D0 + (-0.0000747) * D1) * ((D1/D0 – 1.5) * (0.25) + 1)
*
* => 115.7400832 * ch1 / gain1 / mt -
* 68.1982976 * ch0 / gain0 / mt +
* 0.00012213 * 25600 * (ch1 / gain1 / mt) * 25600 *
* (ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt)
* => -0.000745625 * D0 + 0.0002515625 * D1 + -0.000018675 * D1 * D1 / D0
*
* A = 0.00012213 * 25600 * (ch1 /gain1 / mt) * 25600 *
* (ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt)
* => 0.00012213 * 25600 * (ch1 /gain1 / mt) *
* (ch1 /gain1 / mt) / (ch0 / gain0 / mt)
* => 0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) /
* (ch0 / gain0)
* => 0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) *
* gain0 / ch0
* => 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /ch0
* => (6.44 * ch1 / gain1 + 19.088 * ch0 / gain0 -
* 0.47808 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0) /
* mt
*
* lx = (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) /
* mt + A
* => (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) /
* mt + 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /
* ch0
* Else
* lx = 0.001193 * D0 - 0.0000747 * D1
*
* => (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0 +
* 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0) /
* mt
*
* For (0.87 <= D1/D0 < 1.00)
* lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 0.87) * (0.385) + 1)
* => (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 *
* 100 * ch1 / gain1 / mt) * ((D1/D0 - 0.87) * (0.385) + 1)
* => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
* ((D1/D0 - 0.87) * (0.385) + 1)
* => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
* (0.385 * D1/D0 - 0.66505)
* => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
* (0.385 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) - 0.66505)
* => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
* (9856 * ch1 / gain1 / mt / (25600 * ch0 / gain0 / mt) + 0.66505)
* => 13.118336 * ch1 / (gain1 * mt)
* + 22.66064768 * ch0 / (gain0 * mt)
* + 8931.90144 * ch1 * ch1 * gain0 /
* (25600 * ch0 * gain1 * gain1 * mt)
* + 0.602694912 * ch1 / (gain1 * mt)
*
* => [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1)
* + 22.66064768 * ch0 / gain0
* + 13.721030912 * ch1 / gain1
* ] / mt
*
* For (D1/D0 >= 1.00)
*
* lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 2.0) * (-0.05) + 1)
* => (0.001331* D0 + 0.0000354 * D1) * (-0.05D1/D0 + 1.1)
* => (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 *
* 100 * ch1 / gain1 / mt) * (-0.05D1/D0 + 1.1)
* => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
* (-0.05 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) + 1.1)
* => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
* (-1280 * ch1 / (gain1 * mt * 25600 * ch0 / gain0 / mt) + 1.1)
* => (34.0736 * ch0 * -1280 * ch1 * gain0 * mt /( gain0 * mt * gain1 * mt * 25600 * ch0)
* + 34.0736 * 1.1 * ch0 / (gain0 * mt)
* + 0.90624 * ch1 * -1280 * ch1 *gain0 * mt / (gain1 * mt *gain1 * mt * 25600 * ch0)
* + 1.1 * 0.90624 * ch1 / (gain1 * mt)
* => -43614.208 * ch1 / (gain1 * mt * 25600)
* + 37.48096 ch0 / (gain0 * mt)
* - 1159.9872 * ch1 * ch1 * gain0 / (gain1 * gain1 * mt * 25600 * ch0)
* + 0.996864 ch1 / (gain1 * mt)
* => [
* - 0.045312 * ch1 * ch1 * gain0 / (gain1 * gain1 * ch0)
* - 0.706816 * ch1 / gain1
* + 37.48096 ch0 /gain0
* ] * mt
*
*
* So, the first case (D1/D0 < 0.87) can be computed to a form:
*
* lx = (3.126528 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
* 115.7400832 * ch1 / gain1 +
* -68.1982976 * ch0 / gain0
* / mt
*
* Second case (0.87 <= D1/D0 < 1.00) goes to form:
*
* => [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
* 13.721030912 * ch1 / gain1 +
* 22.66064768 * ch0 / gain0
* ] / mt
*
* Third case (D1/D0 >= 1.00) goes to form:
* => [-0.045312 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
* -0.706816 * ch1 / gain1 +
* 37.48096 ch0 /(gain0
* ] / mt
* => (1.91232 * ch1 / gain1 + 30.5408 * ch0 / gain0 +
* [0 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0] ) /
* mt
*
* This can be unified to format:
* lx = [
......@@ -678,19 +597,14 @@ static int bu27034_set_scale(struct bu27034_data *data, int chan,
* ] / mt
*
* For case 1:
* A = 3.126528,
* B = 115.7400832
* C = -68.1982976
* A = -0.47808,
* B = 6.44,
* C = 19.088
*
* For case 2:
* A = 0.3489024
* B = 13.721030912
* C = 22.66064768
*
* For case 3:
* A = -0.045312
* B = -0.706816
* C = 37.48096
* A = 0
* B = 1.91232
* C = 30.5408
*/
struct bu27034_lx_coeff {
......@@ -795,21 +709,16 @@ static int bu27034_fixp_calc_lx(unsigned int ch0, unsigned int ch1,
{
static const struct bu27034_lx_coeff coeff[] = {
{
.A = 31265280, /* 3.126528 */
.B = 1157400832, /*115.7400832 */
.C = 681982976, /* -68.1982976 */
.is_neg = {false, false, true},
.A = 4780800, /* -0.47808 */
.B = 64400000, /* 6.44 */
.C = 190880000, /* 19.088 */
.is_neg = { true, false, false },
}, {
.A = 3489024, /* 0.3489024 */
.B = 137210309, /* 13.721030912 */
.C = 226606476, /* 22.66064768 */
.A = 0, /* 0 */
.B = 19123200, /* 1.91232 */
.C = 305408000, /* 30.5408 */
/* All terms positive */
}, {
.A = 453120, /* -0.045312 */
.B = 7068160, /* -0.706816 */
.C = 374809600, /* 37.48096 */
.is_neg = {true, true, false},
}
},
};
const struct bu27034_lx_coeff *c = &coeff[coeff_idx];
u64 res = 0, terms[3];
......@@ -972,12 +881,10 @@ static int bu27034_get_single_result(struct bu27034_data *data, int chan,
* D1 = data1/ch1_gain/meas_time_ms * 25600
*
* Then:
* if (D1/D0 < 0.87)
* lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 3.45 + 1)
* else if (D1/D0 < 1)
* lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 0.385 + 1)
* else
* lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 2) * -0.05 + 1)
* If (D1/D0 < 1.5)
* lx = (0.001193 * D0 + (-0.0000747) * D1) * ((D1 / D0 – 1.5) * 0.25 + 1)
* Else
* lx = (0.001193 * D0 + (-0.0000747) * D1)
*
* We use it here. Users who have for example some colored lens
* need to modify the calculation but I hope this gives a starting point for
......@@ -1028,12 +935,10 @@ static int bu27034_calc_mlux(struct bu27034_data *data, __le16 *res, int *val)
d1_d0_ratio_scaled /= ch0 * gain1;
}
if (d1_d0_ratio_scaled < 87)
if (d1_d0_ratio_scaled < 150)
ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 0);
else if (d1_d0_ratio_scaled < 100)
ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 1);
else
ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 2);
ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 1);
if (ret < 0)
return ret;
......
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