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Re: [PATCH v3] fbcon: add fbcon=margin:<color> command line option

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  Re: [PATCH v3] fbcon: add fbcon=margin:<color> command line option Geert Uytterhoeven <geert@linux-m68k.org> - 2017-08-18 20:30 +0200
    Re: [PATCH v3] fbcon: add fbcon=margin:<color> command line option David Lechner <david@lechnology.com> - 2017-08-18 21:20 +0200
      Re: [PATCH v3] fbcon: add fbcon=margin:<color> command line option David Lechner <david@lechnology.com> - 2017-08-23 18:00 +0200
      Re: [PATCH v3] fbcon: add fbcon=margin:<color> command line option Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> - 2017-08-23 18:00 +0200

#1715364 — Re: [PATCH v3] fbcon: add fbcon=margin:<color> command line option

Hi David,

On Tue, Aug 1, 2017 at 6:35 PM, David Lechner <david@lechnology.com> wrote:
> This adds a new command line option to select the fbcon margin color.
>
> The motivation for this is screens where black does not blend into the
> physical surroundings of the screen. For example, using an LCD (not the
> backlit kind), white text on a black background is hard to read, so
> inverting the colors is preferred. However, when you do this, most of the
> screen is filled with white but the margins are still filled with black.
> This makes a big, black, backwards 'L' on the screen. By setting
> fbcon=margin:7, the margins will be filled with white and the LCD looks as
> expected.
>
> Signed-off-by: David Lechner <david@lechnology.com>

> --- a/Documentation/fb/fbcon.txt
> +++ b/Documentation/fb/fbcon.txt
> @@ -148,6 +148,13 @@ C. Boot options
>         Actually, the underlying fb driver is totally ignorant of console
>         rotation.
>
> +5. fbcon=margin:<color>
> +
> +       This option specifies the color of the margins. The margins are the
> +       leftover area at the right and the bottom of the screen that are not
> +       used by text. By default, this area will be black. The 'color' value
> +       is 0 to 7 where 0 is black and 7 is white.
> +

Given the standard console palette contains 16 colors, why limit this to
the first 8 colors, and not 0 to 15?

> --- a/drivers/video/console/fbcon.c
> +++ b/drivers/video/console/fbcon.c
> @@ -137,6 +137,7 @@ static int info_idx = -1;
>  /* console rotation */
>  static int initial_rotation;
>  static int fbcon_has_sysfs;
> +static int margin_color;
>
>  static const struct consw fb_con;
>
> @@ -491,6 +492,15 @@ static int __init fb_console_setup(char *this_opt)
>                                 initial_rotation = 0;
>                         continue;
>                 }
> +
> +               if (!strncmp(options, "margin:", 7)) {
> +                       options += 7;
> +                       if (*options)
> +                               margin_color = simple_strtoul(options, &options, 0);
> +                       if (margin_color > 7)
> +                               margin_color = 0;
> +                       continue;
> +               }

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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

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#1715391

On 08/18/2017 01:21 PM, Geert Uytterhoeven wrote:
> Hi David,
> 
> On Tue, Aug 1, 2017 at 6:35 PM, David Lechner <david@lechnology.com> wrote:
>> This adds a new command line option to select the fbcon margin color.
>>
>> The motivation for this is screens where black does not blend into the
>> physical surroundings of the screen. For example, using an LCD (not the
>> backlit kind), white text on a black background is hard to read, so
>> inverting the colors is preferred. However, when you do this, most of the
>> screen is filled with white but the margins are still filled with black.
>> This makes a big, black, backwards 'L' on the screen. By setting
>> fbcon=margin:7, the margins will be filled with white and the LCD looks as
>> expected.
>>
>> Signed-off-by: David Lechner <david@lechnology.com>
> 
>> --- a/Documentation/fb/fbcon.txt
>> +++ b/Documentation/fb/fbcon.txt
>> @@ -148,6 +148,13 @@ C. Boot options
>>          Actually, the underlying fb driver is totally ignorant of console
>>          rotation.
>>
>> +5. fbcon=margin:<color>
>> +
>> +       This option specifies the color of the margins. The margins are the
>> +       leftover area at the right and the bottom of the screen that are not
>> +       used by text. By default, this area will be black. The 'color' value
>> +       is 0 to 7 where 0 is black and 7 is white.
>> +
> 
> Given the standard console palette contains 16 colors, why limit this to
> the first 8 colors, and not 0 to 15?

Good question. I think in some of my previous attempts there was a 0x7 
mask involved somewhere and this is a carryover from that. But, after 
having looked at this again, I don't see a reason for limiting to 7.

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#1718472

On 08/23/2017 10:56 AM, Bartlomiej Zolnierkiewicz wrote:
> 

>>>
>>> Given the standard console palette contains 16 colors, why limit this to
>>> the first 8 colors, and not 0 to 15?
>>
>> Good question. I think in some of my previous attempts there was a 0x7
>> mask involved somewhere and this is a carryover from that. But, after
>> having looked at this again, I don't see a reason for limiting to 7.
> 
> Could you please prepare the incremental patch raising the number of colors
> possible to use?

Yes, I will do this.

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#1718481

Hi,

On Friday, August 18, 2017 02:19:28 PM David Lechner wrote:
> On 08/18/2017 01:21 PM, Geert Uytterhoeven wrote:
> > Hi David,
> > 
> > On Tue, Aug 1, 2017 at 6:35 PM, David Lechner <david@lechnology.com> wrote:
> >> This adds a new command line option to select the fbcon margin color.
> >>
> >> The motivation for this is screens where black does not blend into the
> >> physical surroundings of the screen. For example, using an LCD (not the
> >> backlit kind), white text on a black background is hard to read, so
> >> inverting the colors is preferred. However, when you do this, most of the
> >> screen is filled with white but the margins are still filled with black.
> >> This makes a big, black, backwards 'L' on the screen. By setting
> >> fbcon=margin:7, the margins will be filled with white and the LCD looks as
> >> expected.
> >>
> >> Signed-off-by: David Lechner <david@lechnology.com>
> > 
> >> --- a/Documentation/fb/fbcon.txt
> >> +++ b/Documentation/fb/fbcon.txt
> >> @@ -148,6 +148,13 @@ C. Boot options
> >>          Actually, the underlying fb driver is totally ignorant of console
> >>          rotation.
> >>
> >> +5. fbcon=margin:<color>
> >> +
> >> +       This option specifies the color of the margins. The margins are the
> >> +       leftover area at the right and the bottom of the screen that are not
> >> +       used by text. By default, this area will be black. The 'color' value
> >> +       is 0 to 7 where 0 is black and 7 is white.
> >> +
> > 
> > Given the standard console palette contains 16 colors, why limit this to
> > the first 8 colors, and not 0 to 15?
> 
> Good question. I think in some of my previous attempts there was a 0x7 
> mask involved somewhere and this is a carryover from that. But, after 
> having looked at this again, I don't see a reason for limiting to 7.

Could you please prepare the incremental patch raising the number of colors
possible to use?

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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