linux-kernel - Re: [PATCH 1/2] video: vga16fb: Fix logic that checks for the display standard

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Date:   Sun, 9 Jan 2022 11:02:22 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Javier Martinez Canillas <javierm@...hat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Kris Karas <bugs-a21@...nlit-rail.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>
Subject: Re: [PATCH 1/2] video: vga16fb: Fix logic that checks for the display standard

Hi Javier,

On Fri, Jan 7, 2022 at 9:00 PM Javier Martinez Canillas
<javierm@...hat.com> wrote:
> The vga16fb framebuffer driver supports both Enhanced Graphics Adapter
> (EGA) and Video Graphics Array (VGA) 16 color graphic cards.
>
> But the logic to check whether the EGA or VGA standard are used is not
> correct. It just checks if screen_info.orig_video_isVGA is set, but it
> should check if is set to VIDEO_TYPE_VGAC instead.
>
> This means that it assumes to be VGA even if is set to VIDEO_TYPE_EGAC.
>
> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>

Thanks for your patch!

> --- a/drivers/video/fbdev/vga16fb.c
> +++ b/drivers/video/fbdev/vga16fb.c
> @@ -1332,7 +1332,7 @@ static int vga16fb_probe(struct platform_device *dev)
>         printk(KERN_INFO "vga16fb: mapped to 0x%p\n", info->screen_base);
>         par = info->par;
>
> -       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.

>         par->palette_blanked = 0;
>         par->vesa_blanked = 0;
>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds