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:

quoted

On Mon, 25 Nov 2024 at 09:50, Neil Armstrong [off-list ref] wrote:

quoted

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