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

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Date:   Mon, 17 Jan 2022 20:45:55 +0100
From:   Helge Deller <deller@....de>
To:     Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        "airlied@...il.com" <airlied@...il.com>,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        Javier Martinez Canillas <javierm@...hat.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer

On 1/17/22 17:21, Helge Deller wrote:
> On 1/17/22 16:58, Thomas Zimmermann wrote:
>> Hi
>>
>> Am 17.01.22 um 16:42 schrieb Helge Deller:
>>> [...]
>>>>> c) reintroduce the state where fbcon is fast on fbdev. This is important for non-DRM machines,
>>>>>     either when run on native hardware or in an emulator.
>>>>> d) not break DRM development
>>>>>
>>>>> Especially regarding c) I complained in [1] and got no feedback. I really would like to
>>>>> understand where the actual problems were and what's necessary to fix them.
>>>>>
>>>>> Helge
>>>>>
>>>>> [1] https://lore.kernel.org/r/feea8303-2b83-fc36-972c-4fc8ad723bde@gmx.de
>>
>> Seems like few people read linux-fbdev these days.
>> I suggest to partly revert the patch to the point were performance
>> gets better again.
> Yes, *please*!
> That would solve my biggest concern.
>
> As far as I can see that's only 2 commits to be reverted:
> b3ec8cdf457e - "fbdev: Garbage collect fbdev scrolling acceleration, part 1 (from TODO list)"
> 39aead8373b3 - "fbcon: Disable accelerated scrolling"for-next-next
>
> I think both were not related to any 0-day bug reports (but again, I might be wrong).

I did some more checking...

Both patches are not related to DRM, since no DRM driver sets the
FBINFO_HWACCEL_COPYAREA or FBINFO_HWACCEL_FILLRECT flags.

Reverting those would bring back fbdev performance which I'm worried most about.
And it introduces no (positive or negative) effects on DRM.

I still wonder why those were submitted.
Let's please revert those.

Helge