linux-kernel - [PATCH] hwmon: (adt7475) Handle DT unaware platforms

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Message-Id: <20230418220109.787907-1-chris.packham@alliedtelesis.co.nz>
Date:   Wed, 19 Apr 2023 10:01:09 +1200
From:   Chris Packham <chris.packham@...iedtelesis.co.nz>
To:     jdelvare@...e.com, linux@...ck-us.net, manio@...boo.net
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chris Packham <chris.packham@...iedtelesis.co.nz>
Subject: [PATCH] hwmon: (adt7475) Handle DT unaware platforms

Configuring the pwm polarity via the adi,pwm-active-state property is an
optional feature. On DT aware platforms of_property_read_u32_array()
returns -EINVAL when the property is absent this is checked for and the
driver probe continues without issue.

On DT unaware platfroms of_property_read_u32_array() returns -ENOSYS
which caused the driver probe to dev_warn(). Update the code to deal
with -ENOSYS so that the dev_warn() only occurs when there is a genuine
issue.

Fixes: 86da28eed4fb ("hwmon: (adt7475) Add support for inverting pwm output")
Reported-by: Mariusz Białończyk <manio@...boo.net>
Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
---
 drivers/hwmon/adt7475.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 6e4c92b500b8..af906eee480e 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -1607,6 +1607,13 @@ static int adt7475_set_pwm_polarity(struct i2c_client *client)
 	ret = of_property_read_u32_array(client->dev.of_node,
 					 "adi,pwm-active-state", states,
 					 ARRAY_SIZE(states));
+	/*
+	 * -EINVAL indicates that the property is absent, -ENOSYS indicates
+	 * that the platform lacks DT awareness. Neither of these are errors
+	 * for the optional pwm polarity support.
+	 */
+	if (ret == -EINVAL || ret == -ENOSYS)
+		return 0;
 	if (ret)
 		return ret;
 
@@ -1741,7 +1748,7 @@ static int adt7475_probe(struct i2c_client *client)
 		adt7475_read_pwm(client, i);
 
 	ret = adt7475_set_pwm_polarity(client);
-	if (ret && ret != -EINVAL)
+	if (ret)
 		dev_warn(&client->dev, "Error configuring pwm polarity\n");
 
 	/* Start monitoring */
-- 
2.40.0