linux-kernel - Re: [PATCH v1 1/2] leds: aw200xx: support for hw pattern controllers

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Message-ID: <20240129141927.4shshli37fb3cwen@CAB-WSD-L081021>
Date: Mon, 29 Jan 2024 17:19:27 +0300
From: Dmitry Rokosov <ddrokosov@...utedevices.com>
To: Pavel Machek <pavel@....cz>
CC: Lee Jones <lee@...nel.org>, Martin Kurbanov
	<mmkurbanov@...utedevices.com>, Rob Herring <robh+dt@...nel.org>, Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
	<conor+dt@...nel.org>, Jonathan Corbet <corbet@....net>, Andy Shevchenko
	<andy.shevchenko@...il.com>, <linux-kernel@...r.kernel.org>,
	<linux-leds@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-doc@...r.kernel.org>, <kernel@...utedevices.com>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>
Subject: Re: [PATCH v1 1/2] leds: aw200xx: support for hw pattern controllers

Hello Pavel,

On Sat, Jan 27, 2024 at 12:21:48AM +0100, Pavel Machek wrote:
> Hi!
> 
> > > This led-controller supports 3 pattern controllers for auto breathing or
> > > group dimming control. Each pattern controller can work in auto
> > > breathing or manual control mode. All breathing parameters including
> > > rising/falling slope, on/off time, repeat times, min/max brightness
> > > and so on are configurable.
> > > 
> > > Signed-off-by: Martin Kurbanov <mmkurbanov@...utedevices.com>
> > > ---
> > >  .../testing/sysfs-class-led-driver-aw200xx    | 108 +++
> > >  Documentation/leds/leds-aw200xx.rst           | 274 ++++++++
> > >  drivers/leds/leds-aw200xx.c                   | 649 ++++++++++++++++++
> > >  3 files changed, 1031 insertions(+)
> > >  create mode 100644 Documentation/leds/leds-aw200xx.rst
> > 
> > This interface is bananas.  Exposing an entire register interface to
> > sysfs does not sit will with me at all.  When we add support to a sysfs
> > class, we usually require it to be generic and work across all devices.
> > Adding device specific interfaces is generally decried and to be
> > avoided.  Don't forget, once we commit something to sysfs, it becomes
> > ABI and we have to support it forever.
> 
> If you do git grep hw_pattern, you should get pointers to qcom-lpg
> driver that solves similar problem, with interface that should be
> acceptable.

Thank you for pointing that out. Yes, it's a very similar situation to
ours.

But I haven't observed the merging of this driver. Was it encountering
similar issues with the sysfs interface?

-- 
Thank you,
Dmitry