Re: [PATCH] fbdev: workaround for broken X servers

["Ville Syrjälä" <syrjala@sci.fi>]

On Wed, Nov 03, 2004 at 01:13:39PM +1100, Benjamin Herrenschmidt wrote:
> Hi !
> 
> XFree (and X.org) has both always been broken in their conversion of the DPMS
> blanking mode when passing to the kernel ioctl FBIOBLANK (in fbdev mode).
> 
> This patch makes sure that at least the value passed by userland stays in the
> legal range, which has the side effect that an X DPMS POWERDOWN request will
> result as an fbdev VESA_POWERDOWN request at the fbdev level now, instead of
> an out-of-range value.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> 
> Index: linux-work/drivers/video/fbmem.c
> ===================================================================
> --- linux-work.orig/drivers/video/fbmem.c	2004-10-26 13:15:55.000000000 +1000
> +++ linux-work/drivers/video/fbmem.c	2004-11-03 13:10:41.324932256 +1100
> @@ -748,6 +748,10 @@
>  	u16 *black = NULL;
>  	int err = 0;
>  	
> +	/* Workaround for broken X servers */
> +	if (blank > VESA_POWERDOWN)
> +		blank = VESA_POWERDOWN;
> +
>  	if (info->fbops->fb_blank && !info->fbops->fb_blank(blank, info))
>  		return 0;
>  

This goes against documented behaviour (see fb.h). Also drivers/char/vt.c 
seems to agree with fb.h, as do at least atyfb and matroxfb. I also used 
the vesa level+1 convention in DirectFB. So AFAICS this patch would 
confuse console power management, XFree86/X.Org, DirectFB and some fb 
drivers.

-- 
Ville Syrjälä
syrjala@sci.fi
http://www.sci.fi/~syrjala/


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