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Message-ID: <63018892-68e8-01b6-1e8f-853892e15c97@gmx.de>
Date:   Tue, 1 Feb 2022 12:01:35 +0100
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Subject: Re: [PATCH 03/21] fbcon: Restore fbcon scrolling acceleration
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To:     Daniel Vetter <daniel.vetter@ffwll.ch>
Cc:     DRI Development <dri-devel@lists.freedesktop.org>,
        Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
        linux-fbdev@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        stable@vger.kernel.org, Claudio Suarez <cssk@net-c.es>,
        Dave Airlie <airlied@gmail.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Pavel Machek <pavel@ucw.cz>, Sam Ravnborg <sam@ravnborg.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Sven Schnelle <svens@stackframe.org>,
        Gerd Hoffmann <kraxel@redhat.com>
References: <20220131210552.482606-1-daniel.vetter@ffwll.ch>
 <20220131210552.482606-4-daniel.vetter@ffwll.ch>
 <9c22b709-cbcf-6a29-a45e-5a57ba0b9c14@gmx.de>
 <CAKMK7uGvOVe8kkJCTkQBEFw+3i2iAMANsyG9vGqZkcROZ9he4A@mail.gmail.com>
From:   Helge Deller <deller@gmx.de>
In-Reply-To: <CAKMK7uGvOVe8kkJCTkQBEFw+3i2iAMANsyG9vGqZkcROZ9he4A@mail.gmail.com>
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On 2/1/22 11:36, Daniel Vetter wrote:
> On Tue, Feb 1, 2022 at 11:16 AM Helge Deller <deller@gmx.de> wrote:
>>
>> On 1/31/22 22:05, Daniel Vetter wrote:
>>> This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
>>> scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
>>> option.
>>
>> you have two trivial copy-n-paste errors in this patch which still prev=
ent the
>> console acceleration.
>
> Duh :-(
>
> But before we dig into details I think the big picture would be
> better. I honestly don't like the #ifdef pile here that much.

Me neither.
The ifdefs give a better separation, but prevents that the compiler
checks the various paths when building.

> I wonder whether your approach, also with GETVX/YRES adjusted
> somehow, wouldn't look cleaner?
I think so.
You wouldn't even need to touch GETVX/YRES because the compiler
will optimize/reduce it from

#define GETVYRES(s,i) ({                           \
        (s =3D=3D SCROLL_REDRAW || s =3D=3D SCROLL_MOVE) ? \
        (i)->var.yres : (i)->var.yres_virtual; })

to just become:

#define GETVYRES(s,i) ((i)->var.yres)

> Like I said in the cover letter I got mostly distracted with fbcon
> locking last week, not really with this one here at all, so maybe
> going with your 4 (or 2 if we squash them like I did here) patches is
> neater?

The benefit of my patch series was, that it could be easily backported fir=
st,
and then cleaned up afterwards. Even a small additional backport patch to =
disable
the fbcon acceleration for DRM in the old releases would be easy.
But I'm not insisting on backporting the patches, if we find good way forw=
ard.

So, either with the 4 (or 2) patches would be OK for me (or even your appr=
oach).

Helge