linux-kernel - Re: [PATCH v10 2/2] leds: as3668: Driver for the ams Osram 4-channel i2c LED driver

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Message-ID: <20251125125842.GB1127788@google.com>
Date: Tue, 25 Nov 2025 12:58:42 +0000
From: Lee Jones <lee@...nel.org>
To: Lukas Timmermann <linux@...mermann.space>
Cc: pavel@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, linux-leds@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 2/2] leds: as3668: Driver for the ams Osram 4-channel
 i2c LED driver

On Fri, 21 Nov 2025, Lukas Timmermann wrote:

> On Thu, Nov 20, 2025 at 12:07:04PM +0000, Lee Jones wrote:
> > On Mon, 17 Nov 2025, Lukas Timmermann wrote:
> > 
> > > Since there were no existing drivers for the AS3668 or related devices,
> > > a new driver was introduced in a separate file. Similar devices were
> > > reviewed, but none shared enough characteristics to justify code reuse.
> > > As a result, this driver is written specifically for the AS3668.
> > > 
> > > Signed-off-by: Lukas Timmermann <linux@...mermann.space>
> > > ---
> > >  MAINTAINERS                |   1 +
> > >  drivers/leds/Kconfig       |  13 +++
> > >  drivers/leds/Makefile      |   1 +
> > >  drivers/leds/leds-as3668.c | 222 +++++++++++++++++++++++++++++++++++++
> > >  4 files changed, 237 insertions(+)
> > >  create mode 100644 drivers/leds/leds-as3668.c

[...] 

> > > +	if (reg < 0) {
> > > +		dev_err(&as3668->client->dev, "failed to read channel modes\n");
> > > +		return;
> > > +	}
> > > +
> > > +	switch (led_id) {
> > > +	case 0:
> > > +		reg &= ~AS3668_CURR1_MODE_MASK;
> > > +		reg |= FIELD_PREP(AS3668_CURR1_MODE_MASK, mode);
> > > +		break;
> > > +	case 1:
> > > +		reg &= ~AS3668_CURR2_MODE_MASK;
> > > +		reg |= FIELD_PREP(AS3668_CURR2_MODE_MASK, mode);
> > > +		break;
> > > +	case 2:
> > > +		reg &= ~AS3668_CURR3_MODE_MASK;
> > > +		reg |= FIELD_PREP(AS3668_CURR3_MODE_MASK, mode);
> > > +		break;
> > > +	case 3:
> > > +		reg &= ~AS3668_CURR4_MODE_MASK;
> > > +		reg |= FIELD_PREP(AS3668_CURR4_MODE_MASK, mode);
> > > +		break;
> > > +	default:
> > > +		return;
> > > +	}
> > > +
> > > +	err = i2c_smbus_write_byte_data(as3668->client, AS3668_CURR_MODE_REG, reg);
> > 
> > Either it's an error or it's not.  Why isn't it being propagated?
> > 
> My patch had a dev_err() call here. It's missing in your citation.
> Was using dev_err() here wrong?

Yes.  It's preferable that you propagate (return) the error.

If you don't do that, it's just a warning.

-- 
Lee Jones [李琼斯]