[PATCH] fbmem: really support wildcard video=options for all fbdev drivers

[PATCH] fbmem: really support wildcard video=options for all fbdev drivers

[Olaf Hering]

Documentation/fb/modedb.txt states that video=option should be
considered a global option. But video_setup and fb_get_options are not
coded that way. Instead its required to boot with video=driver:option to
set a given option in drvier.  This is cumbersome because it requires to
know in advance which driver will be active for a given board/kernel.

The following patch implements the documented catchall for the fbdev
drivers. It is now possible to boot with video=XxY without the need to
know the active driver in advance. The specific case it tries to fix is
syslinux in the SUSE installer which offers a menu to set a display
resolution. Right now this just appends the vga= option the kernel. But
in addition to vga= it should be possible to pass a generic video=XxY
for all framebuffer/drm drivers. With this change forcing a certain
window size of VM displays is now much easier.

Today the video= option is stored in a global fb_mode_option. But
unfortunately only drm uses it.

Note: this change introduces a small memleak if video=option is actually
used because fb_mode_option is const. Most drivers use strsep to get to
individual options. This could be fixed in a followup patch which always
releases the option string in every caller of fb_get_options.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 drivers/video/fbmem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 010d191..cde4619 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1930,6 +1930,9 @@ int fb_get_options(const char *name, char **option)
 				options = opt + name_len + 1;
 		}
 	}
+	/* No match, pass global option */
+	if (!options && option && fb_mode_option)
+		options = kstrdup(fb_mode_option, GFP_KERNEL);
 	if (options && !strncmp(options, "off", 3))
 		retval = 1;
 

Re: [PATCH] fbmem: really support wildcard video=options for all fbdev drivers

[Geert Uytterhoeven]

On Sun, Dec 15, 2013 at 9:40 PM, Olaf Hering <olaf@aepfle.de> wrote:
> Documentation/fb/modedb.txt states that video=option should be
> considered a global option. But video_setup and fb_get_options are not
> coded that way. Instead its required to boot with video=driver:option to
> set a given option in drvier.  This is cumbersome because it requires to
> know in advance which driver will be active for a given board/kernel.

That's an interesting finding: this definitely was working fine a few years ago.
Unfortunately I have no idea when I used it recently. I'm 100% sure I used it
with ps3fb ca. 5 years ago.

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

Re: [PATCH] fbmem: really support wildcard video=options for all fbdev drivers

[Tomi Valkeinen]

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On 2013-12-15 22:40, Olaf Hering wrote:
> Documentation/fb/modedb.txt states that video=option should be
> considered a global option. But video_setup and fb_get_options are not
> coded that way. Instead its required to boot with video=driver:option to
> set a given option in drvier.  This is cumbersome because it requires to
> know in advance which driver will be active for a given board/kernel.
> 
> The following patch implements the documented catchall for the fbdev
> drivers. It is now possible to boot with video=XxY without the need to
> know the active driver in advance. The specific case it tries to fix is
> syslinux in the SUSE installer which offers a menu to set a display
> resolution. Right now this just appends the vga= option the kernel. But
> in addition to vga= it should be possible to pass a generic video=XxY
> for all framebuffer/drm drivers. With this change forcing a certain
> window size of VM displays is now much easier.
> 
> Today the video= option is stored in a global fb_mode_option. But
> unfortunately only drm uses it.
> 
> Note: this change introduces a small memleak if video=option is actually
> used because fb_mode_option is const. Most drivers use strsep to get to
> individual options. This could be fixed in a followup patch which always
> releases the option string in every caller of fb_get_options.
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> ---
>  drivers/video/fbmem.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
> index 010d191..cde4619 100644
> --- a/drivers/video/fbmem.c
> +++ b/drivers/video/fbmem.c
> @@ -1930,6 +1930,9 @@ int fb_get_options(const char *name, char **option)
>  				options = opt + name_len + 1;
>  		}
>  	}
> +	/* No match, pass global option */
> +	if (!options && option && fb_mode_option)
> +		options = kstrdup(fb_mode_option, GFP_KERNEL);
>  	if (options && !strncmp(options, "off", 3))
>  		retval = 1;
>  
> 

Queued for 3.14.

 Tomi



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