Re: [PATCH 2.6.17-rc6-mm2] fbdev: tag by scantype in sysfs

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

Daniel THOMPSON wrote:
> Geert Uytterhoeven wrote:
>> On Fri, 23 Jun 2006, Daniel THOMPSON wrote:
>>> On Tue, 2006-06-20 at 18:29 +0800, Antonino A. Daplas wrote:
>>>>  /sys/class/graphics---fb0
>>>>                     :
>>>>                     --fb1
>>>>                     :
>>>>                     --fbn
>>>>                     :
>>>>                     --mode0---640x480@60
>>>>                     :       :
>>>>                     :       --1024x768@60
>>>>                     :  
>>>>                     --mode1
>>> So the directory mode0 contains all the modes that fb0 is capable of
>>> displaying? Can't that go inside fb0?
>> Let's hope not, as most machines/fb combos don't have enough RAM to store all
>> modes the fb is capable of.
> 
> Fair point.
> 
> By default the existing modes includes only the VESA standard modes,
> although I would expect drivers for TV-like hardware to override the
> mode list to get the supportable CEA-851 standards instead.
>

It only includes modes that are in the driver's private mode list. For
most drivers, that's one entry, for others with EDID, it can be as
much as 40 (near-maximum the EDID block is capable of), but typically
less than 10.
 
> I confess I'm having a great deal of difficulty trying to think of any
> way to update the mode list while sticking to one file, one value.

We can unbind fb[n] from display[n], echo the mode we want added to an 'x'
file one by one, and the modes we don't want into a 'y' file. Finally,
we can bind fb[n] back to display[n]. It's ugly, but can work.

After giving it some thought, sysfs is just not appropriate to serve the
needs of the framebuffer system. So I'll leave fbsysfs untouched for now and
just find/invent more appropriate interfaces.

Tony

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