Re: Patch to add mode setting to sysfs

[Jon Smirl <jonsmirl@gmail.com>]

On Fri, 18 Feb 2005 08:04:46 +0800, Antonino A. Daplas
<adaplas@hotpop.com> wrote:
> This is dangerous.  For one, if the mode in info->var does not match any of
> the entries in the modelist, you can get a screwed up display.  Secondly,
> fbcon refers to info->modelist to store settings for each console.  Thus
> it is better to check first if the mode in the modelist is currently in use.
> 
> A safer way is to loop through each entries of the old modelist, call
> fb_set_var() with the FB_ACTIVATE_INV_MODE set in var->activate. This
> process will safely remove each mode from the modelist.  Not all entries
> will be deleted of course. After that, loop through each entries of the new
> modedb array, and use fb_add_videomode() to add each entry to the modelist.

Radeon hardware has an interrupt that is not hooked up in radeonfb
that can tell if the monitor has been switched. Hook a radeon to a KVM
switch and flip the switch. We should get an interrupt. Use the
interrupt to trigger a hotplug event. Hotplug event will set a new
list of modes into radeonfb. All of the old modes have to be deleted,
they probably don't exist in the new monitor.

At this point fbcon needs to get a modelist change event. It can then
find_mode() to find a new mode that is close to what it was using. So
the problem seems to be that disp->mode holds a pointer to the mode
instead of a copy of the mode. I'll try changing this to a copy. Does
fbcon really need to know the entire mode structure or could it work
with just the resolution?

I'd feel more comfortable if fbcon used a well defined interface to
fbdev instead of having access to all of fbdev's internal structures.
I tried modifying fbcon to use DRM but it is completely tied to fbdev.
Anyway, the current code is much better than it was in 2.4.

-- 
Jon Smirl
jonsmirl@gmail.com


-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click