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From 33f339b70f020273ea40fb3c5d7b65697446bd6c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Beh=C3=BAn?= <kabel@kernel.org>
Date: Mon, 16 Oct 2023 15:28:06 +0200
Subject: [PATCH 08/17] leds: turris-omnia: Fix brightness setting and trigger
 activating
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I have improperly refactored commits
  4d5ed2621c24 ("leds: turris-omnia: Make set_brightness() more efficient")
and
  aaf38273cf76 ("leds: turris-omnia: Support HW controlled mode via private trigger")
after Lee requested a change in API semantics of the new functions I
introduced in commit
  28350bc0ac77 ("leds: turris-omnia: Do not use SMBUS calls").

Before the change, the function omnia_cmd_write_u8() returned 0 on
success, and afterwards it returned a positive value (number of bytes
written). The latter version was applied, but the following commits did
not properly account for this change.

This results in non-functional LED's .brightness_set_blocking() and
trigger's .activate() methods.

The main reasoning behind the semantics change was that read/write
methods should return the number of read/written bytes on success.
It was pointed to me [1] that this is not always true (for example the
regmap API does not do so), and since the driver never uses this number
of read/written bytes information, I decided to fix this issue by
changing the functions to the original semantics (return 0 on success).

[1] https://lore.kernel.org/linux-gpio/ZQnn+Gi0xVlsGCYA@smile.fi.intel.com/

Fixes: 28350bc0ac77 ("leds: turris-omnia: Do not use SMBUS calls")
Signed-off-by: Marek Behún <kabel@kernel.org>
---
 drivers/leds/leds-turris-omnia.c | 37 +++++++++++++++++---------------
 1 file changed, 20 insertions(+), 17 deletions(-)

--- a/drivers/leds/leds-turris-omnia.c
+++ b/drivers/leds/leds-turris-omnia.c
@@ -60,8 +60,11 @@ struct omnia_leds {
 static int omnia_cmd_write_u8(const struct i2c_client *client, u8 cmd, u8 val)
 {
        u8 buf[2] = { cmd, val };
+       int ret;
+
+       ret = i2c_master_send(client, buf, sizeof(buf));
 
-       return i2c_master_send(client, buf, sizeof(buf));
+       return ret < 0 ? ret : 0;
 }
 
 static int omnia_cmd_read_raw(struct i2c_adapter *adapter, u8 addr, u8 cmd,
@@ -81,7 +84,7 @@ static int omnia_cmd_read_raw(struct i2c
 
        ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
        if (likely(ret == ARRAY_SIZE(msgs)))
-               return len;
+               return 0;
        else if (ret < 0)
                return ret;
        else
@@ -91,11 +94,11 @@ static int omnia_cmd_read_raw(struct i2c
 static int omnia_cmd_read_u8(const struct i2c_client *client, u8 cmd)
 {
        u8 reply;
-       int ret;
+       int err;
 
-       ret = omnia_cmd_read_raw(client->adapter, client->addr, cmd, &reply, 1);
-       if (ret < 0)
-               return ret;
+       err = omnia_cmd_read_raw(client->adapter, client->addr, cmd, &reply, 1);
+       if (err)
+               return err;
 
        return reply;
 }
@@ -236,7 +239,7 @@ static void omnia_hwtrig_deactivate(stru
 
        mutex_unlock(&leds->lock);
 
-       if (err < 0)
+       if (err)
                dev_err(cdev->dev, "Cannot put LED to software mode: %i\n",
                        err);
 }
@@ -302,7 +305,7 @@ static int omnia_led_register(struct i2c
        ret = omnia_cmd_write_u8(client, CMD_LED_MODE,
                                 CMD_LED_MODE_LED(led->reg) |
                                 CMD_LED_MODE_USER);
-       if (ret < 0) {
+       if (ret) {
                dev_err(dev, "Cannot set LED %pOF to software mode: %i\n", np,
                        ret);
                return ret;
@@ -311,7 +314,7 @@ static int omnia_led_register(struct i2c
        /* disable the LED */
        ret = omnia_cmd_write_u8(client, CMD_LED_STATE,
                                 CMD_LED_STATE_LED(led->reg));
-       if (ret < 0) {
+       if (ret) {
                dev_err(dev, "Cannot set LED %pOF brightness: %i\n", np, ret);
                return ret;
        }
@@ -364,7 +367,7 @@ static ssize_t brightness_store(struct d
 {
        struct i2c_client *client = to_i2c_client(dev);
        unsigned long brightness;
-       int ret;
+       int err;
 
        if (kstrtoul(buf, 10, &brightness))
                return -EINVAL;
@@ -372,9 +375,9 @@ static ssize_t brightness_store(struct d
        if (brightness > 100)
                return -EINVAL;
 
-       ret = omnia_cmd_write_u8(client, CMD_LED_SET_BRIGHTNESS, brightness);
+       err = omnia_cmd_write_u8(client, CMD_LED_SET_BRIGHTNESS, brightness);
 
-       return ret < 0 ? ret : count;
+       return err ?: count;
 }
 static DEVICE_ATTR_RW(brightness);
 
@@ -403,7 +406,7 @@ static ssize_t gamma_correction_store(st
        struct i2c_client *client = to_i2c_client(dev);
        struct omnia_leds *leds = i2c_get_clientdata(client);
        bool val;
-       int ret;
+       int err;
 
        if (!leds->has_gamma_correction)
                return -EOPNOTSUPP;
@@ -411,9 +414,9 @@ static ssize_t gamma_correction_store(st
        if (kstrtobool(buf, &val) < 0)
                return -EINVAL;
 
-       ret = omnia_cmd_write_u8(client, CMD_SET_GAMMA_CORRECTION, val);
+       err = omnia_cmd_write_u8(client, CMD_SET_GAMMA_CORRECTION, val);
 
-       return ret < 0 ? ret : count;
+       return err ?: count;
 }
 static DEVICE_ATTR_RW(gamma_correction);
 
@@ -431,7 +434,7 @@ static int omnia_mcu_get_features(const
 
        err = omnia_cmd_read_raw(client->adapter, OMNIA_MCU_I2C_ADDR,
                                 CMD_GET_STATUS_WORD, &reply, sizeof(reply));
-       if (err < 0)
+       if (err)
                return err;
 
        /* Check whether MCU firmware supports the CMD_GET_FEAUTRES command */
@@ -440,7 +443,7 @@ static int omnia_mcu_get_features(const
 
        err = omnia_cmd_read_raw(client->adapter, OMNIA_MCU_I2C_ADDR,
                                 CMD_GET_FEATURES, &reply, sizeof(reply));
-       if (err < 0)
+       if (err)
                return err;
 
        return le16_to_cpu(reply);