Re: [Linux-fbdev-devel] [PATCH] fbdev: Fix usage of blank value passed to fb_blank

["Antonino A. Daplas" <adaplas@gmail.com>]

Ville Syrjälä wrote:
> On Sun, Jan 29, 2006 at 10:18:19AM +0800, Antonino A. Daplas wrote:
>> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
>> index d2dede6..5bed0fb 100644
>> --- a/drivers/video/fbmem.c
>> +++ b/drivers/video/fbmem.c
>> @@ -843,6 +843,19 @@ fb_blank(struct fb_info *info, int blank
>>  {	
>>   	int ret = -EINVAL;
>>  
>> +	/*
>> +	 * The framebuffer core supports 5 blanking levels (FB_BLANK), whereas
>> +	 * VESA defined only 4.  The extra level, FB_BLANK_NORMAL, is a
>> +	 * console invention and is not related to power management.
>> +	 * Unfortunately, fb_blank callers, especially X, pass VESA constants
>> +	 * leading to undefined behavior.
> 
> Since when? X.Org uses numbers 0,2,3,4 which match the FB_BLANK 
> constants not the VESA constants.
> 

How about if we silently convert FB_BLANK_NORMAL requests to
FB_BLANK_VSYNC_SUSPEND, would that work?

Tony

PS: Soft blanking is very difficult, if not impossible, to
implement correctly kernel-side, so we can either fail (current
code), silently fail but return success, or convert to the next
blank level.