linux-kernel - Re: [PATCH v2 0/4] media: meson: Add support for the Amlogic GE2D Accelerator Unit

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Message-ID: <CACRpkdZnpjas-WYuXhJ_mwCTqTP5DpWHcnNmGpdCQjrr3xGnYg@mail.gmail.com>
Date:   Thu, 5 Nov 2020 08:53:39 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Neil Armstrong <narmstrong@...libre.com>,
        Todd Kjos <tkjos@...gle.com>
Cc:     Hans Verkuil <hverkuil@...all.nl>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        John Stultz <john.stultz@...aro.org>
Subject: Re: [PATCH v2 0/4] media: meson: Add support for the Amlogic GE2D
 Accelerator Unit

Hi Neil,

this is just a drive-by question and I'm looping in Todd in the hopes for
a discussion or clarification.

On Fri, Oct 30, 2020 at 3:37 PM Neil Armstrong <narmstrong@...libre.com> wrote:

> The GE2D is a 2D accelerator with various features like configurable blitter
> with alpha blending, frame rotation, scaling, format conversion and colorspace
> conversion.
>
> The driver implements a Memory2Memory VB2 V4L2 streaming device permitting:
> - 0, 90, 180, 270deg rotation
> - horizontal/vertical flipping
> - source cropping
> - destination compositing
> - 32bit/24bit/16bit format conversion
>
> This adds the support for the GE2D version found in the AXG SoCs Family.

We are starting to see a bunch of these really nicely abstracted blitters
and other 2D-accelerators now.

Is stuff like Android going to pick up and use this to blit and blend
generic buffers?

Or is this in essence a camera and/or video out accelerator thing?

The placement of this driver in drivers/media makes me think that
it is for cameras or video output, but the functionality is actually
quite generic.

I've been half-guessing that userspace like Android actually mostly
use GPUs to composit their graphics, but IIUC this can sometimes be
used for 2D compositing, and when used will often be quicker and/or
more energy efficient than using a GPU for the same task.

Yours,
Linus Walleij