linux-kernel - [PATCH] rtc: pcf2127: add error checking and message when disabling POR0

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Date:   Mon, 17 Jan 2022 17:56:24 -0500
From:   Hugo Villeneuve <hugo@...ovil.com>
To:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     hugo@...ovil.com, Hugo Villeneuve <hvilleneuve@...onoff.com>,
        linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] rtc: pcf2127: add error checking and message when disabling POR0

From: Hugo Villeneuve <hvilleneuve@...onoff.com>

If PCF2127 device is absent from the I2C bus, or if there is a
communication problem, disabling POR0 may fail silently and we
still continue with probing the device. In that case, abort probe
operation and display an error message.

Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
---
 drivers/rtc/rtc-pcf2127.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index 81a5b1f2e68c..e6d0838ccfe3 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -690,8 +690,12 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 	 * The "Power-On Reset Override" facility prevents the RTC to do a reset
 	 * after power on. For normal operation the PORO must be disabled.
 	 */
-	regmap_clear_bits(pcf2127->regmap, PCF2127_REG_CTRL1,
+	ret = regmap_clear_bits(pcf2127->regmap, PCF2127_REG_CTRL1,
 				PCF2127_BIT_CTRL1_POR_OVRD);
+	if (ret < 0) {
+		dev_err(dev, "PORO disabling failed\n");
+		return ret;
+	}
 
 	ret = regmap_read(pcf2127->regmap, PCF2127_REG_CLKOUT, &val);
 	if (ret < 0)
-- 
2.30.2