[PATCH v2] drivers: adc: fix return value if timeout occurs

[Francois Berder]

Because unsigned integers cannot be negative,
timeout variable is never less than zero. Hence, checks
in Amlogic Meson ADC driver to detect timeouts always
evaluated to false. Fix that.

Signed-off-by: Francois Berder <fberder at outlook.fr>
---
Changes for v2:
   - Replace timeout handling logic by regmap_read_poll_timeout

 drivers/adc/meson-saradc.c | 33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/drivers/adc/meson-saradc.c b/drivers/adc/meson-saradc.c
index 1a45a3a265..b36f09cdb1 100644
--- a/drivers/adc/meson-saradc.c
+++ b/drivers/adc/meson-saradc.c
@@ -192,7 +192,8 @@ meson_saradc_get_fifo_count(struct meson_saradc_priv *priv)
 
 static int meson_saradc_lock(struct meson_saradc_priv *priv)
 {
-	uint val, timeout = 10000;
+	uint val;
+	int ret;
 
 	/* prevent BL30 from using the SAR ADC while we are using it */
 	regmap_update_bits(priv->regmap, MESON_SAR_ADC_DELAY,
@@ -202,17 +203,14 @@ static int meson_saradc_lock(struct meson_saradc_priv *priv)
 	/*
 	 * wait until BL30 releases it's lock (so we can use the SAR ADC)
 	 */
-	do {
-		udelay(1);
-		regmap_read(priv->regmap, MESON_SAR_ADC_DELAY, &val);
-	} while (val & MESON_SAR_ADC_DELAY_BL30_BUSY && timeout--);
-
-	if (timeout < 0) {
+	ret =
+	    regmap_read_poll_timeout(priv->regmap, MESON_SAR_ADC_DELAY, val,
+				     val & MESON_SAR_ADC_DELAY_BL30_BUSY, 1,
+				     10);
+	if (ret)
 		printf("Timeout while waiting for BL30 unlock\n");
-		return -ETIMEDOUT;
-	}
 
-	return 0;
+	return ret;
 }
 
 static void meson_saradc_unlock(struct meson_saradc_priv *priv)
@@ -246,22 +244,19 @@ static int meson_saradc_calib_val(struct meson_saradc_priv *priv, int val)
 
 static int meson_saradc_wait_busy_clear(struct meson_saradc_priv *priv)
 {
-	uint regval, timeout = 10000;
+	uint regval;
 
 	/*
 	 * NOTE: we need a small delay before reading the status, otherwise
 	 * the sample engine may not have started internally (which would
 	 * seem to us that sampling is already finished).
 	 */
-	do {
-		udelay(1);
-		regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
-	} while (FIELD_GET(MESON_SAR_ADC_REG0_BUSY_MASK, regval) && timeout--);
+	udelay(1);
 
-	if (timeout < 0)
-		return -ETIMEDOUT;
-
-	return 0;
+	return regmap_read_poll_timeout(priv->regmap, MESON_SAR_ADC_REG0,
+					regval,
+					FIELD_GET(MESON_SAR_ADC_REG0_BUSY_MASK,
+						  regval), 1, 10);
 }
 
 static int meson_saradc_read_raw_sample(struct meson_saradc_priv *priv,
-- 
2.25.1