linux-kernel - Re: [PATCH 00/17] fbdev: Remove FBINFO_DEFAULT and FBINFO_FLAG

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Date:   Tue, 11 Jul 2023 16:47:44 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     deller@....de, javierm@...hat.com, linux-fbdev@...r.kernel.org,
        kvm@...r.kernel.org, linux-hyperv@...r.kernel.org,
        linux-sh@...r.kernel.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        linux-geode@...ts.infradead.org, dri-devel@...ts.freedesktop.org,
        linux-input@...r.kernel.org, linux-nvidia@...ts.surfsouth.com,
        linux-omap@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org
Subject: Re: [PATCH 00/17] fbdev: Remove FBINFO_DEFAULT and
 FBINFO_FLAG_DEFAULT flags

Hi Thomas,

On Tue, Jul 11, 2023 at 08:24:40AM +0200, Thomas Zimmermann wrote:
> Hi Sam
> 
> Am 10.07.23 um 19:19 schrieb Sam Ravnborg:
> > Hi Thomas,
> > 
> > On Mon, Jul 10, 2023 at 02:50:04PM +0200, Thomas Zimmermann wrote:
> > > Remove the unused flags FBINFO_DEFAULT and FBINFO_FLAG_DEFAULT from
> > > fbdev and drivers, as briefly discussed at [1]. Both flags were maybe
> > > useful when fbdev had special handling for driver modules. With
> > > commit 376b3ff54c9a ("fbdev: Nuke FBINFO_MODULE"), they are both 0
> > > and have no further effect.
> > > 
> > > Patches 1 to 7 remove FBINFO_DEFAULT from drivers. Patches 2 to 5
> > > split this by the way the fb_info struct is being allocated. All flags
> > > are cleared to zero during the allocation.
> > > 
> > > Patches 8 to 16 do the same for FBINFO_FLAG_DEFAULT. Patch 8 fixes
> > > an actual bug in how arch/sh uses the tokne for struct fb_videomode,
> > > which is unrelated.
> > > 
> > > Patch 17 removes both flag constants from <linux/fb.h>
> > 
> > We have a few more flags that are unused - should they be nuked too?
> > FBINFO_HWACCEL_FILLRECT
> > FBINFO_HWACCEL_ROTATE
> > FBINFO_HWACCEL_XPAN
> 
> It seems those are there for completeness. Nothing sets _ROTATE, the others
> are simply never checked. According to the comments, some are required, some
> are optional. I don't know what that means.
> 
> IIRC there were complains about performance when Daniel tried to remove
> fbcon acceleration, so not all _HWACCEL_ flags are unneeded.
> 
> Leaving them in for reference/completeness might be an option; or not. I
> have no strong feelings about those flags.
> 
> > 
> > Unused as in no references from fbdev/core/*
> > 
> > I would rather see one series nuke all unused FBINFO flags in one go.
> > Assuming my quick grep are right and the above can be dropped.
> 
> I would not want to extend this series. I'm removing _DEFAULT as it's
> absolutely pointless and confusing.

OK, makes sense and thanks for the explanation.

The series is:
Acked-by: Sam Ravnborg <sam@...nborg.org>