Re: Use of 'reserved' fields in var_screeninfo

[Kevin Hilman <khilman@mvista.com>]

Geert Uytterhoeven wrote:
> On Mon, 14 Nov 2005, Kevin Hilman wrote:
> 
>>I've got a question about the purpose of the reserved fields in the
>>var_screeninfo struct:
>>
>>struct fb_var_screeninfo {
>>	[ ... ]
>>	__u32 reserved[5];		/* Reserved for future compatibility */
>>};
>>
>>What are these reserved for?  Is it appropriate for drivers to use these for
> 
> 
> They are reserved for future expansion.
> 
> 
>>additional, HW-specific values that are then made available to the VSCREENINFO
>>ioctls?
> 
> 
> Not really, only for generic info that's useful for multiple drivers.
> What do you want to export there?
> 

I'm just weighing the options of whether I should just add a new
device-specific ioctl, or try to export this as part of the var_screeninfo.

I've got some HW which has the ability display/blend up to 4 video/graphics
sources within a root display window.  I'd like to export this x,y offset
(which is independent of the xoffset,yoffset for the virtual/visual stuff).
Also, it has a per-source scaling factor I'd like to export.

Kevin




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