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

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Message-ID: <20251013085514.512508-1-christian@klarinett.li>
Date: Mon, 13 Oct 2025 10:54:42 +0200
From: Christian Hitz <christian@...rinett.li>
To: Jacek Anaszewski <jacek.anaszewski@...il.com>
Cc: Christian Hitz <christian@...rinett.li>,
	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 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.

Fixes: 242b81170fb8 ("leds: lp50xx: Add the LP50XX family of the RGB LED driver")

> 
> >   
> >   	led_config_lo = bank_enable_mask;
> >   	led_config_hi = bank_enable_mask >> 8;
> > @@ -405,7 +403,7 @@ static int lp50xx_probe_leds(struct fwnode_handle *child, struct lp50xx *priv,
> >   			return ret;
> >   		}
> >   
> > -		ret = lp50xx_set_banks(priv, led_banks);
> > +		ret = lp50xx_set_banks(priv, led_banks, num_leds);
> >   		if (ret) {
> >   			dev_err(priv->dev, "Cannot setup banked LEDs\n");
> >   			return ret;
> 
> Reviewed-by: Jacek Anaszewski <jacek.anaszewski@...il.com>
> 
> -- 
> Best regards,
> Jacek Anaszewski

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