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-rw-r--r--board/samsung/common/exynos5-dt-types.c38
1 files changed, 37 insertions, 1 deletions
diff --git a/board/samsung/common/exynos5-dt-types.c b/board/samsung/common/exynos5-dt-types.c
index 7c1271d654..516c32923e 100644
--- a/board/samsung/common/exynos5-dt-types.c
+++ b/board/samsung/common/exynos5-dt-types.c
@@ -57,12 +57,48 @@ static unsigned int odroid_get_rev(void)
return 0;
}
+/*
+ * Read ADC at least twice and check the resuls. If regulator providing voltage
+ * on to measured point was just turned on, first reads might require time
+ * to stabilize.
+ */
+static int odroid_get_adc_val(unsigned int *adcval)
+{
+ unsigned int adcval_prev = 0;
+ int ret, retries = 20;
+
+ ret = adc_channel_single_shot("adc", CONFIG_ODROID_REV_AIN,
+ &adcval_prev);
+ if (ret)
+ return ret;
+
+ while (retries--) {
+ mdelay(5);
+
+ ret = adc_channel_single_shot("adc", CONFIG_ODROID_REV_AIN,
+ adcval);
+ if (ret)
+ return ret;
+
+ /*
+ * If difference between ADC reads is less than 3%,
+ * accept the result
+ */
+ if ((100 * abs(*adcval - adcval_prev) / adcval_prev) < 3)
+ return ret;
+
+ adcval_prev = *adcval;
+ }
+
+ return ret;
+}
+
static int odroid_get_board_type(void)
{
unsigned int adcval;
int ret, i;
- ret = adc_channel_single_shot("adc", CONFIG_ODROID_REV_AIN, &adcval);
+ ret = odroid_get_adc_val(&adcval);
if (ret)
goto rev_default;