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i2c/tsl2550: Fix lux value in dark environment

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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. 

Signed-off-by: Michele Jr De Candia <michele.decandia@valueteam.com>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Michele Jr De Candia 2009-07-28 16:33:03 +02:00 committed by Jean Delvare
parent 4733fd328f
commit 96f699ad09
1 changed files with 10 additions and 7 deletions
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17
drivers/i2c/chips/tsl2550.c
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@ -27,7 +27,7 @@
#include <linux/delay.h>
#define TSL2550_DRV_NAME "tsl2550"
#define DRIVER_VERSION "1.1.1"
#define DRIVER_VERSION "1.1.2"
/*
* Defines
@ -189,13 +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 (c1 <= c0)
if (c0) {
r = c1 * 128 / c0;
/* Calculate LUX */
lux = ((c0 - c1) * ratio_lut[r]) / 256;
/* Calculate LUX */
lux = ((c0 - c1) * ratio_lut[r]) / 256;
} else
lux = 0;
else
return -EAGAIN;
/* LUX range check */
return lux > TSL2550_MAX_LUX ? TSL2550_MAX_LUX : lux;