Re: [PATCH 2/2] Revert "fbcon: Disable accelerated scrolling"

[Helge Deller]

On 1/19/22 15:01, Linus Torvalds wrote:
> On Wed, Jan 19, 2022 at 2:29 PM Helge Deller <deller@xxxxxx> wrote:
>>
>>>>
>>>> Ah, no, that was just the soft scrollback code I was thinking of, which
>>
>> Right.
>> That was commit 973c096f6a85 and it was about vgacon, not fbcon.
>
> No, fbcon had some bug too, although I've paged out the details. See
> commit 50145474f6ef ("fbcon: remove soft scrollback code").

Yes, but those bugs didn't affected

> If I remember correctly (and it's entirely possible that I don't), the
> whole "softback_lines" logic had serious problems with resizing the
> console (or maybe changing the font size).

Right.
I'm not asking to revert any soft scrollback functions.

It's about if you allow to use the fbdev-drivers hardware acceleration
to move parts of the screen or if you are stuck to software memcpy() and
repainting instead.
None of the bug reports touched that part.

> There may have been some other bad interaction with
> foreground/background consoles too, I forget.

I think that is independend if you use hardware acceleration or not.

Helge