diff options
| -rw-r--r-- | include/linux/mfd/ti_am335x_tscadc.h | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h index 25f2c611ab01..4befdb85dd9c 100644 --- a/include/linux/mfd/ti_am335x_tscadc.h +++ b/include/linux/mfd/ti_am335x_tscadc.h @@ -125,13 +125,18 @@ #define TOTAL_CHANNELS 8 /* -* ADC runs at 3MHz, and it takes -* 15 cycles to latch one data output. -* Hence the idle time for ADC to -* process one sample data would be -* around 5 micro seconds. -*/ -#define IDLE_TIMEOUT 5 /* microsec */ + * time in us for processing a single channel, calculated as follows: + * + * num cycles = open delay + (sample delay + conv time) * averaging + * + * num cycles: 152 + (1 + 13) * 16 = 376 + * + * clock frequency: 26MHz / 8 = 3.25MHz + * clock period: 1 / 3.25MHz = 308ns + * + * processing time: 376 * 308ns = 116us + */ +#define IDLE_TIMEOUT 116 /* microsec */ #define TSCADC_CELLS 2 |