[PATCH v7 0/2] leds-lp50xx: Support reg to set multi_index.

[PATCH v7 0/2] leds-lp50xx: Support reg to set multi_index.

[Johan Adolfsson]

Since devicetree nodes are (sometimes?) processed in reverse order,
support reg as the actual multi_index index so yo get well defined
color order presented in the multi_index file.
Not sure if reusing reg for this is the correct way or if another
property such as "multi_index" or similar should be used instead.
Looks like reg is used for similar things at least.
Or should the whole "reverse the devicetree" problem be fixed instead?
Update bindings to match implementation, and add description for the
reg property.

Signed-off-by: Johan Adolfsson <johan.adolfsson@axis.com>
---
Changes in v7:
- Skip leftover initialization of multi_index.
- Fix devcietree description and update commit message.
- Link to v6: https://lore.kernel.org/r/20250616-led-fix-v6-0-b9df5b63505d@axis.com

Changes in v6:
- Remove maxItems från devicetree binding
- Link to v5: https://lore.kernel.org/r/20250616-led-fix-v5-0-f59c740831ab@axis.com

Changes in v5:
- Fail if reg is not set.
- Adjust devicetree schema, use items.
- Link to v4: https://lore.kernel.org/r/20250526-led-fix-v4-0-33345f6c4a78@axis.com

Changes in v4:
- Remove maxItems from devicetree schema, not compatible with minimum
  and maximum.
- Link to v3: https://lore.kernel.org/r/20250523-led-fix-v3-0-86d2690d2698@axis.com

Changes in v3:
- Update To and Cc.
- Rephrase bindings descriptions, add constraints.
- Link to v2: https://lore.kernel.org/r/20250522-led-fix-v2-0-652046323ec3@axis.com

Changes in v2:
- Avoid duplicate assignment. dev_err and return -EINVAL on error.
- Update bindings doc.
- Link to v1: https://lore.kernel.org/r/20250506-led-fix-v1-1-56a39b55a7fc@axis.com

---
Johan Adolfsson (2):
      leds: leds-lp50xx: Handle reg to get correct multi_index
      dt-bindings: leds: lp50xx: Document child reg, fix example

 .../devicetree/bindings/leds/leds-lp50xx.yaml         | 19 ++++++++++++-------
 drivers/leds/leds-lp50xx.c                            | 11 ++++++++++-
 2 files changed, 22 insertions(+), 8 deletions(-)
---
base-commit: 0ff41df1cb268fc69e703a08a57ee14ae967d0ca
change-id: 20250225-led-fix-444fb544584a

Best regards,
-- 
Johan Adolfsson <johan.adolfsson@axis.com>

[PATCH v7 1/2] leds: leds-lp50xx: Handle reg to get correct multi_index

[Johan Adolfsson]

mc_subled used for multi_index needs well defined array indexes,
to guarantee the desired result, use reg for that.

If devicetree child nodes is processed in random or reverse order
you may end up with multi_index "blue green red" instead of the expected
"red green blue".
If user space apps uses multi_index to deduce how to control the leds
they would most likely be broken without this patch if devicetree
processing is reversed (which it appears to be).

arch/arm/boot/dts/aspeed/aspeed-bmc-facebook-fuji.dts has reg set
but I don't see how it can have worked without this change.

If reg is not set, an error is returned,
If reg is out of range, an error is returned.
reg within led child nodes starts with 0, to map to the iout in each bank.

Signed-off-by: Johan Adolfsson <johan.adolfsson@axis.com>
---
 drivers/leds/leds-lp50xx.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/leds-lp50xx.c b/drivers/leds/leds-lp50xx.c
index 02cb1565a9fb..94f8ef6b482c 100644
--- a/drivers/leds/leds-lp50xx.c
+++ b/drivers/leds/leds-lp50xx.c
@@ -476,6 +476,7 @@ static int lp50xx_probe_dt(struct lp50xx *priv)
 			return -ENOMEM;
 
 		fwnode_for_each_child_node(child, led_node) {
+			int multi_index;
 			ret = fwnode_property_read_u32(led_node, "color",
 						       &color_id);
 			if (ret) {
@@ -483,8 +484,16 @@ static int lp50xx_probe_dt(struct lp50xx *priv)
 				dev_err(priv->dev, "Cannot read color\n");
 				return ret;
 			}
+			ret = fwnode_property_read_u32(led_node, "reg", &multi_index);
+			if (ret != 0) {
+				dev_err(priv->dev, "reg must be set\n");
+				return -EINVAL;
+			} else if (multi_index >= LP50XX_LEDS_PER_MODULE) {
+				dev_err(priv->dev, "reg %i out of range\n", multi_index);
+				return -EINVAL;
+			}
 
-			mc_led_info[num_colors].color_index = color_id;
+			mc_led_info[multi_index].color_index = color_id;
 			num_colors++;
 		}
 

-- 
2.30.2

[PATCH v7 2/2] dt-bindings: leds: lp50xx: Document child reg, fix example

[Johan Adolfsson]

The led child reg node is the index within the bank, document that
and update the example accordingly.
The reg property in child node is limited to 0-2 since there are 3 leds
per bank, previous value in example was speculative.

Signed-off-by: Johan Adolfsson <johan.adolfsson@axis.com>
---
 .../devicetree/bindings/leds/leds-lp50xx.yaml         | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/leds/leds-lp50xx.yaml b/Documentation/devicetree/bindings/leds/leds-lp50xx.yaml
index 402c25424525..23f809906ba7 100644
--- a/Documentation/devicetree/bindings/leds/leds-lp50xx.yaml
+++ b/Documentation/devicetree/bindings/leds/leds-lp50xx.yaml
@@ -81,7 +81,12 @@ patternProperties:
 
         properties:
           reg:
-            maxItems: 1
+            items:
+              - minimum: 0
+                maximum: 2
+
+            description:
+              This property denotes the index within the LED bank.
 
         required:
           - reg
@@ -138,18 +143,18 @@ examples:
                 color = <LED_COLOR_ID_RGB>;
                 function = LED_FUNCTION_STANDBY;
 
-                led@3 {
-                    reg = <0x3>;
+                led@0 {
+                    reg = <0x0>;
                     color = <LED_COLOR_ID_RED>;
                 };
 
-                led@4 {
-                    reg = <0x4>;
+                led@1 {
+                    reg = <0x1>;
                     color = <LED_COLOR_ID_GREEN>;
                 };
 
-                led@5 {
-                    reg = <0x5>;
+                led@2 {
+                    reg = <0x2>;
                     color = <LED_COLOR_ID_BLUE>;
                 };
             };

-- 
2.30.2

Re: [PATCH v7 2/2] dt-bindings: leds: lp50xx: Document child reg, fix example

[Conor Dooley]

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On Tue, Jun 17, 2025 at 12:23:55PM +0200, Johan Adolfsson wrote:
> The led child reg node is the index within the bank, document that
> and update the example accordingly.
> The reg property in child node is limited to 0-2 since there are 3 leds
> per bank, previous value in example was speculative.

Acked-by: Conor Dooley <conor.dooley@microchip.com>

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Re: [PATCH v7 1/2] leds: leds-lp50xx: Handle reg to get correct multi_index

[Jacek Anaszewski]

Hi Johan,

Thanks for the update.

On 6/17/25 12:23, Johan Adolfsson wrote:
> mc_subled used for multi_index needs well defined array indexes,
> to guarantee the desired result, use reg for that.
> 
> If devicetree child nodes is processed in random or reverse order
> you may end up with multi_index "blue green red" instead of the expected
> "red green blue".
> If user space apps uses multi_index to deduce how to control the leds
> they would most likely be broken without this patch if devicetree
> processing is reversed (which it appears to be).
> 
> arch/arm/boot/dts/aspeed/aspeed-bmc-facebook-fuji.dts has reg set
> but I don't see how it can have worked without this change.
> 
> If reg is not set, an error is returned,
> If reg is out of range, an error is returned.
> reg within led child nodes starts with 0, to map to the iout in each bank.
> 
> Signed-off-by: Johan Adolfsson <johan.adolfsson@axis.com>
> ---
>   drivers/leds/leds-lp50xx.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/leds/leds-lp50xx.c b/drivers/leds/leds-lp50xx.c
> index 02cb1565a9fb..94f8ef6b482c 100644
> --- a/drivers/leds/leds-lp50xx.c
> +++ b/drivers/leds/leds-lp50xx.c
> @@ -476,6 +476,7 @@ static int lp50xx_probe_dt(struct lp50xx *priv)
>   			return -ENOMEM;
>   
>   		fwnode_for_each_child_node(child, led_node) {
> +			int multi_index;
>   			ret = fwnode_property_read_u32(led_node, "color",
>   						       &color_id);
>   			if (ret) {
> @@ -483,8 +484,16 @@ static int lp50xx_probe_dt(struct lp50xx *priv)
>   				dev_err(priv->dev, "Cannot read color\n");
>   				return ret;
>   			}
> +			ret = fwnode_property_read_u32(led_node, "reg", &multi_index);
> +			if (ret != 0) {
> +				dev_err(priv->dev, "reg must be set\n");
> +				return -EINVAL;
> +			} else if (multi_index >= LP50XX_LEDS_PER_MODULE) {
> +				dev_err(priv->dev, "reg %i out of range\n", multi_index);
> +				return -EINVAL;
> +			}
>   
> -			mc_led_info[num_colors].color_index = color_id;
> +			mc_led_info[multi_index].color_index = color_id;
>   			num_colors++;
>   		}
>   
> 

Reviewed-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

-- 
Best regards,
Jacek Anaszewski

Re: [PATCH v7 0/2] leds-lp50xx: Support reg to set multi_index.

[Lee Jones]

On Tue, 17 Jun 2025 12:23:53 +0200, Johan Adolfsson wrote:
> Since devicetree nodes are (sometimes?) processed in reverse order,
> support reg as the actual multi_index index so yo get well defined
> color order presented in the multi_index file.
> Not sure if reusing reg for this is the correct way or if another
> property such as "multi_index" or similar should be used instead.
> Looks like reg is used for similar things at least.
> Or should the whole "reverse the devicetree" problem be fixed instead?
> Update bindings to match implementation, and add description for the
> reg property.
> 
> [...]

Applied, thanks!

[1/2] leds: leds-lp50xx: Handle reg to get correct multi_index
      commit: f0022183bfd939f7d3c669cca0bf3aade233c9a5
[2/2] dt-bindings: leds: lp50xx: Document child reg, fix example
      commit: d07927c0ca918a6825ef46cb7c012dbc102ac352

--
Lee Jones [李琼斯]