linux-kernel - Re: [PATCH] leds: leds-lp50xx: allow LED 0 to be added to module bank

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Message-ID: <c68111e0-e651-44ee-af7f-737a408fe080@gmail.com>
Date: Mon, 13 Oct 2025 19:35:40 +0200
From: Jacek Anaszewski <jacek.anaszewski@...il.com>
To: Christian Hitz <christian@...rinett.li>
Cc: Lee Jones <lee@...nel.org>, Pavel Machek <pavel@...nel.org>,
 Christian Hitz <christian.hitz@....ch>, stable@...r.kernel.org,
 linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] leds: leds-lp50xx: allow LED 0 to be added to module bank

On 10/13/25 10:54, Christian Hitz wrote:
> On Sat, 11 Oct 2025 14:16:16 +0200 Jacek Anaszewski <jacek.anaszewski@...il.com> wrote:
> 
>> Hi Christian,
>>
>> On 10/8/25 14:32, Christian Hitz wrote:
>>> From: Christian Hitz <christian.hitz@....ch>
>>>
>>> led_banks contains LED module number(s) that should be grouped into the
>>> module bank. led_banks is 0-initialized.
>>> By checking the led_banks entries for 0, un-set entries are detected.
>>> But a 0-entry also indicates that LED module 0 should be grouped into the
>>> module bank.
>>>
>>> By only iterating over the available entries no check for unused entries
>>> is required and LED module 0 can be added to bank.
>>>
>>> Signed-off-by: Christian Hitz <christian.hitz@....ch>
>>> Cc: stable@...r.kernel.org
>>> ---
>>>    drivers/leds/leds-lp50xx.c | 10 ++++------
>>>    1 file changed, 4 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/leds/leds-lp50xx.c b/drivers/leds/leds-lp50xx.c
>>> index 94f8ef6b482c..d50c7f3e8f99 100644
>>> --- a/drivers/leds/leds-lp50xx.c
>>> +++ b/drivers/leds/leds-lp50xx.c
>>> @@ -341,17 +341,15 @@ static int lp50xx_brightness_set(struct led_classdev *cdev,
>>>    	return ret;
>>>    }
>>>    
>>> -static int lp50xx_set_banks(struct lp50xx *priv, u32 led_banks[])
>>> +static int lp50xx_set_banks(struct lp50xx *priv, u32 led_banks[], int num_leds)
>>>    {
>>>    	u8 led_config_lo, led_config_hi;
>>>    	u32 bank_enable_mask = 0;
>>>    	int ret;
>>>    	int i;
>>>    
>>> -	for (i = 0; i < priv->chip_info->max_modules; i++) {
>>> -		if (led_banks[i])
>>> -			bank_enable_mask |= (1 << led_banks[i]);
>>> -	}
>>> +	for (i = 0; i < num_leds; i++)
>>> +		bank_enable_mask |= (1 << led_banks[i]);
>>
>> Probably the first idea was to have a bitmask indicating which bank
>> to enable, but it ended up in having array of bank ids in DT with no
>> related adjustment in the driver.
>>
>> This patch deserves Fixes tag.
> 
> This code has not changed since the inital introduction of this driver.

Yeah, I had on mind design approach changes between subsequent
versions of the patch that was adding the driver.

> Fixes: 242b81170fb8 ("leds: lp50xx: Add the LP50XX family of the RGB LED driver")
-- 
Best regards,
Jacek Anaszewski