From: "Kris Karas (Bug reporting)" <bugs-a21@moonlit-rail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
Javier Martinez Canillas <javierm@redhat.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
DRI Development <dri-devel@lists.freedesktop.org>,
Linux Fbdev development list <linux-fbdev@vger.kernel.org>
Subject: Re: [PATCH 1/2] video: vga16fb: Fix logic that checks for the display standard
Date: Sun, 9 Jan 2022 15:20:07 -0500 [thread overview]
Message-ID: <4fac9803-50d2-0c83-8b49-a1b2058d7da0@moonlit-rail.com> (raw)
In-Reply-To: <CAMuHMdXG3xOUrzOoRQVgpb4MmuQKJ1y3yPXv=p4AiNEohrzZug@mail.gmail.com>
Groetje, Geert,
Geert Uytterhoeven wrote:
>
>> - par->isVGA = screen_info.orig_video_isVGA;
>> + par->isVGA = screen_info.orig_video_isVGA == VIDEO_TYPE_VGAC;
> All non-x86 architectures (except for 2 MIPS platforms) treat
> orig_video_isVGA as a boolean flag, and just assign 1 to it.
> Hence this change would break them.
I see a bit of a conflict with using orig_video_isVGA as a boolean. All
the modern architecture-agnostic driver code, such as sysfb,
sysfb_simplefb, and efifb, all use and expect orig_video_isVGA to be an
integer. On the other hand, the VGA driver for XEN first sets
orig_video_isVGA = 1 (boolean), and then VIDEO_TYPE_VLFB or
VIDEO_TYPE_EFI (integer). Overloading the definition for
orig_video_isVGA to be both boolean and integer - within the same file -
seems like a recipe for bugs to me.
That said, I think that wrapping the par->isVGA code, above, within a
check for CONFIG_X86 seems safe and expedient. But I would be much
happier if the non-x86 architectures would set it to a proper integer
value (even if fake) that coincidentally satisfies boolean "true", say
VIDEO_TYPE_VGAC; that way, there would be no confusion as to data type
in all the more recent architecture-agnostic framebuffer code.
Kris
next prev parent reply other threads:[~2022-01-09 20:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-07 11:07 [PATCH 0/2] video: A couple of fixes for the vga16fb driver Javier Martinez Canillas
2022-01-07 11:07 ` [PATCH 1/2] video: vga16fb: Fix logic that checks for the display standard Javier Martinez Canillas
2022-01-09 10:02 ` Geert Uytterhoeven
2022-01-09 20:20 ` Kris Karas (Bug reporting) [this message]
2022-01-10 8:22 ` Javier Martinez Canillas
2022-01-07 11:07 ` [PATCH 2/2] video: vga16fb: Only probe for EGA and VGA 16 color graphic cards Javier Martinez Canillas
2022-01-09 10:01 ` Geert Uytterhoeven
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