leds: lm3601x: Calculate max_brightness and brightness properly

The torch_current_max should be checked not exceeding the upper bound.
If it does, throw a warning message and set to LM3601X_MAX_TORCH_I_UA.

LM3601x torch brigthness register (LM3601X_LED_TORCH_REG) takes 0 as the
minimum output (2.4 mA). However, 0 of led_brightness means LED_OFF.
Adding a -1 offset to brightness before writing to brightness
register, so when users write minimum brightness (1), it sets lm3601x
output the minimum.

Signed-off-by: Jack Chen <zenghuchen@google.com>
Link: https://lore.kernel.org/r/20240704191500.766846-1-zenghuchen@google.com
Signed-off-by: Lee Jones <lee@kernel.org>

diff --git a/drivers/leds/flash/leds-lm3601x.c b/drivers/leds/flash/leds-lm3601x.c
index 7e93c447fec5c176b7b9293660d0fb33226e3c89..1a6b9ee9e582908abb13af25608e9d04a646b980 100644 (file)
--- a/drivers/leds/flash/leds-lm3601x.c
+++ b/drivers/leds/flash/leds-lm3601x.c
@@ -190,7 +190,7 @@ static int lm3601x_brightness_set(struct led_classdev *cdev,
                goto out;
        }
 
-       ret = regmap_write(led->regmap, LM3601X_LED_TORCH_REG, brightness);
+       ret = regmap_write(led->regmap, LM3601X_LED_TORCH_REG, brightness - 1);
        if (ret < 0)
                goto out;
 
@@ -341,8 +341,9 @@ static int lm3601x_register_leds(struct lm3601x_led *led,
 
        led_cdev = &led->fled_cdev.led_cdev;
        led_cdev->brightness_set_blocking = lm3601x_brightness_set;
-       led_cdev->max_brightness = DIV_ROUND_UP(led->torch_current_max,
-                                               LM3601X_TORCH_REG_DIV);
+       led_cdev->max_brightness =
+                       DIV_ROUND_UP(led->torch_current_max - LM3601X_MIN_TORCH_I_UA + 1,
+                                    LM3601X_TORCH_REG_DIV);
        led_cdev->flags |= LED_DEV_CAP_FLASH;
 
        init_data.fwnode = fwnode;
@@ -386,6 +387,14 @@ static int lm3601x_parse_node(struct lm3601x_led *led,
                goto out_err;
        }
 
+       if (led->torch_current_max > LM3601X_MAX_TORCH_I_UA) {
+               dev_warn(&led->client->dev,
+                        "Max torch current set too high (%d vs %d)\n",
+                        led->torch_current_max,
+                        LM3601X_MAX_TORCH_I_UA);
+               led->torch_current_max = LM3601X_MAX_TORCH_I_UA;
+       }
+
        ret = fwnode_property_read_u32(child, "flash-max-microamp",
                                &led->flash_current_max);
        if (ret) {