linux-kernel - Re: [PATCH 2/5] gpu: drm: adp: Add Apple Display Pipe driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241125-gabby-furry-rooster-cf28a9@houat>
Date: Mon, 25 Nov 2024 16:28:00 +0100
From: Maxime Ripard <mripard@...nel.org>
To: Hector Martin <marcan@...can.st>
Cc: Sasha Finkelstein <fnkl.kernel@...il.com>, neil.armstrong@...aro.org, 
	Sven Peter <sven@...npeter.dev>, Alyssa Rosenzweig <alyssa@...enzweig.io>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jessica Zhang <quic_jesszhan@...cinc.com>, asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Janne Grunau <j@...nau.net>
Subject: Re: [PATCH 2/5] gpu: drm: adp: Add Apple Display Pipe driver

On Mon, Nov 25, 2024 at 11:24:25PM +0900, Hector Martin wrote:
> 
> 
> On 2024/11/25 20:24, Sasha Finkelstein wrote:
> > On Mon, 25 Nov 2024 at 09:50, Neil Armstrong <neil.armstrong@...aro.org> wrote:
> >>
> >> So this controller only supports a single mode ???????
> >>
> > Most likely. On all devices it is connected to a single built-in display.
> 
> More specifically, the controller obviously supports multiple modes but
> it is pre-initialized by the bootloader for the single hardwired
> display's only mode. So as far as the driver is concerned, there is a
> single possible mode, and there's no point in trying to be more generic
> if there is no hardware that would use that.

It's not only about being generic, it's also about fitting nicely in the
usual abstractions. You could also always register a single panel, with
a single timing set, and the driver would never see anything else. And
still fall within the usual pattern.

> In general, it is not possible/practical to be generic for reverse
> engineered hardware with no specs documenting how to drive it
> generically. You just can't know how to implement the options that are
> never used in practice. I spent a lot of time on exceptions to this
> rule for the GPIO and SPI controllers, and that's not going to happen
> for more complex hardware like MIPI DSI.

How is GPIO or SPI even remotely related to that discussion? We are
different maintainers, with different concerns, and different things to
care about.

Also, "My way or the highway" is never a great discussion opener.

Maxime

Download attachment "signature.asc" of type "application/pgp-signature" (274 bytes)