Jonathan Cameron wrote:
Michele De Candia (VT) wrote:
Hi all,
I've tested TSL2550 driver and I've found a bug: when light is off,
returned value from tsl2550_calculate_lux function is -1 when it should
be 0 (sensor correctly read that light was off).
I think the bug is that a zero c0 value (approximated value of ch0) is
misinterpreted as an error.
I'm attaching you a patch that fixes the bug.
Regards,
Michele Jr De Candia
Sounds reasonable, but I think a stray line got away in your patch (see below)
Not to mention, if the c1 <= c0 check is still valid, should you not also
confirm that c1 == 0 as well? Perhaps reverse the ordering?
That's right. A new patch can be found in attachment.
if (c1 <= c0)
if(c0) {
r = c1* 128 / c0;
lux = ((c0 - c1) * ratio_lut[r]) / 256;
} else
lux = 0;
else
return -1;
Signed-off-by: Michele Jr De Candia <michele.decandia@xxxxxxxxxxxxx>
diff --git a/drivers/i2c/chips/tsl2550.c b/drivers/i2c/chips/tsl2550.c
index 1a9cc13..6bad072 100644
--- a/drivers/i2c/chips/tsl2550.c
+++ b/drivers/i2c/chips/tsl2550.c
@@ -189,10 +189,16 @@ static int tsl2550_calculate_lux(u8 ch0, u8 ch1)
u8 r = 128;
/* Avoid division by 0 and count 1 cannot be greater than count 0 */
- if (c0 && (c1 <= c0))
- r = c1 * 128 / c0;
- else
- return -1;
+ if (c0) {
+ if (c1 <= c0)
+ r = c1 * 128 / c0;
+ else
+ return -1;
+
+ /* Calculate LUX */
+ lux = ((c0 - c1) * ratio_lut[r]) / 256;
+ }
+ else lux = 0;
This last line should have been removed I think?
/* Calculate LUX */
lux = ((c0 - c1) * ratio_lut[r]) / 256;
---
Jonathan Cameron
Than
Signed-off-by: Michele Jr De Candia <michele.decandia@xxxxxxxxxxxxx>
diff --git a/drivers/i2c/chips/tsl2550.c b/drivers/i2c/chips/tsl2550.c
index 1a9cc13..c4e1104 100644
--- a/drivers/i2c/chips/tsl2550.c
+++ b/drivers/i2c/chips/tsl2550.c
@@ -189,14 +189,17 @@ static int tsl2550_calculate_lux(u8 ch0, u8 ch1)
u8 r = 128;
/* Avoid division by 0 and count 1 cannot be greater than count 0 */
- if (c0 && (c1 <= c0))
- r = c1 * 128 / c0;
+ if (c1 <= c0)
+ if (c0) {
+ r = c1 * 128 / c0;
+
+ /* Calculate LUX */
+ lux = ((c0 - c1) * ratio_lut[r]) / 256;
+ } else
+ lux = 0;
else
return -1;
- /* Calculate LUX */
- lux = ((c0 - c1) * ratio_lut[r]) / 256;
-
/* LUX range check */
return lux > TSL2550_MAX_LUX ? TSL2550_MAX_LUX : lux;
}
