linux-kernel - Re: [PATCH 2/4] backlight: ktz8866: add slave handler

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Message-ID: <20250418181442.207436-1-mitltlatltl@gmail.com>
Date: Sat, 19 Apr 2025 02:14:41 +0800
From: Pengyu Luo <mitltlatltl@...il.com>
To: krzk@...nel.org
Cc: conor+dt@...nel.org,
	danielt@...nel.org,
	deller@....de,
	devicetree@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	jingoohan1@...il.com,
	krzk+dt@...nel.org,
	lee@...nel.org,
	linux-fbdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-leds@...r.kernel.org,
	lujianhua000@...il.com,
	mitltlatltl@...il.com,
	pavel@...nel.org,
	robh@...nel.org
Subject: Re: [PATCH 2/4] backlight: ktz8866: add slave handler

On Mon, Apr 7, 2025 at 6:00 PM Krzysztof Kozlowski <krzk@...nel.org> wrote:
> On 07/04/2025 11:51, Pengyu Luo wrote:
> > Kinetic ktz8866, found in many android devices, nowadays, some oem use
> > dual ktz8866 to support a larger panel and  higher brightness, original
> > driver would only handle half backlight region on these devices,
> > registering it twice is unreasonable, so adding the slave handler to
> > support it.

[...]

> 
> I wrote on IRC - phandle to express the relationship between hardware -
> and I do not see it implemented.
> 
> If you have devices depending on each other, you need to express it -
> for links, for resource dependencies etc. phandle is for that usually.
> Or OF graph. Or parent-child relationship.
> 

I got you now, as a non-native speaker, I often misunderstood the first
time, you expected that accessing node phandle in relationship or graph
way, I did only access node phandle regardless of relationship or graph
description, I only implied it in compatible string, but there would be
a better way.

> You did not provide any description of the hardware in the binding, so I
> really do not have any idea what is this setup thus how to represent it.
> Use hardware terms, diagrams etc to explain the hardware in the bindings
> commit. What are the addresses? Are there any shared resources? What
> buses are devices sitting on, etc.

Agree.

Best wishes,
Pengyu