linux-kernel - Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer

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Message-ID: <20220118095352.xsb6fqacw4p276c5@sirius.home.kraxel.org>
Date:   Tue, 18 Jan 2022 10:53:52 +0100
From:   Gerd Hoffmann <kraxel@...hat.com>
To:     Pekka Paalanen <ppaalanen@...il.com>
Cc:     Sven Schnelle <svens@...ckframe.org>,
        dri-devel@...ts.freedesktop.org, Helge Deller <deller@....de>,
        linux-fbdev@...r.kernel.org,
        Thomas Zimmermann <tzimmermann@...e.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer

On Tue, Jan 18, 2022 at 10:33:23AM +0200, Pekka Paalanen wrote:
> On Mon, 17 Jan 2022 19:47:39 +0100
> Sven Schnelle <svens@...ckframe.org> wrote:
> 
> > I also tested the speed on my Thinkpad X1 with Intel graphics, and there
> > a dmesg with 919 lines one the text console took about 2s to display. In
> > x11, i measure 22ms. This might be unfair because encoding might be
> > different, but i cannot confirm the 'memcpy' is faster than hardware
> > blitting' point. I think if that would be the case, no-one would care
> > about 2D acceleration.
> 
> I think that is an extremely unfair comparison, because a graphical
> terminal app is not going to render every line of text streamed to it.
> It probably renders only the final view alone if you simply run
> 'dmesg', skipping the first 800-900 lines completely.

Probably more like "render on every vblank", but yes, unlike fbcon it
surely wouldn't render every single character sent to the terminal.

Also acceleration on modern hardware is more like "compose window
content using the 3d engine" than "use 2d blitter to scroll the window".

> Maybe fbcon should do the same when presented with a flood of text,
> but I don't know how or why it works like it works.

fbcon could do the same, i.e. render to fbdev in a 60Hz timer instead of
doing it synchronously.

take care,
  Gerd