linux-kernel - Re: [PATCH v5 0/7] leds: Add virtual LED group driver with priority arbitration

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Message-ID: <20260106165947.GA2233601-robh@kernel.org>
Date: Tue, 6 Jan 2026 10:59:47 -0600
From: Rob Herring <robh@...nel.org>
To: Jonathan Brophy <professorjonny98@...il.com>
Cc: lee Jones <lee@...nel.org>, Pavel Machek <pavel@...nel.org>,
	Andriy Shevencho <andriy.shevchenko@...ux.intel.com>,
	Jonathan Brophy <professor_jonny@...mail.com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Radoslav Tsvetkov <rtsvetkov@...dotech.eu>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-leds@...r.kernel.org
Subject: Re: [PATCH v5 0/7] leds: Add virtual LED group driver with priority
 arbitration

On Tue, Dec 30, 2025 at 09:23:13PM +1300, Jonathan Brophy wrote:
> From: Jonathan Brophy <professor_jonny@...mail.com>
> 
> This patch series introduces a new LED driver that implements virtual LED
> groups with priority-based arbitration for shared physical LEDs. The driver
> provides a multicolor LED interface while solving the problem of multiple
> subsystems needing to control the same physical LEDs.
> 
> Key features:
> - Winner-takes-all priority-based arbitration
> - Full multicolor LED ABI compliance
> - Two operating modes (multicolor and standard/fixed-color)
> - Deterministic channel ordering by LED_COLOR_ID
> - Comprehensive debugfs telemetry (when CONFIG_DEBUG_FS enabled)
> - Optimized memory footprint (~200 bytes per LED in production builds)
> 
> Use cases:
> - System status indicators with boot/error/update priority levels
> - RGB lighting with coordinated control
> - Multi-element LED arrays unified into single logical controls

I still don't really understand what you are trying to do. You need to 
tell a story not just some bullet lists. What is it you want to do that 
you can't currently support. I would start from the top level. What do 
you need to be able to do from userspace. Describe what you need to do 
not in terms of "here's how I solved/implemented it" but what does the 
current interface lack. IOW, define the problem in a way we can provide 
alternate solutions.

I see "virtual" and that screams "doesn't belong in DT" to me. I assume 
there is some physical property of why certain LEDs are grouped 
together. Convince me that the board designer would define 
the grouping rather than the user running Linux. Multi-color LEDs are 
physically packaged together for example, so defining in DT makes sense.

If you can split this up into smaller series/features, that would help 
with your upstreaming. Otherwise, it looks like a huge pile to 
try to understand and we'll likely just move on to other series which 
are easier to review.

Rob