[Linux-fbdev-devel] Re: [linux-fbdev] [ANNOUNCE] fbgen "2"

[James S. <jsi...@tr...>]

> I have two problems with this: 
> (1) Please remove ifdef CONFIG_PM around that. pm.h provides dummy
>     pm_* functions when pm is disabled, so you do not have to check
>     CONFIG_PM in driver sources. But if structure does not have this
>     pm_fb field, you must :-(

Okay. I will fix that.

> (2) Is there any reason for having this pointer in this structure at
>     all? Does anybody except driver itself need such thing? You can 
>     have couple of fbdevs pointing to one pm_dev, just because of 
>     they live on same device and cannot be powered up independently.

Yes! 

   One their are devices that need to do more than just blank the screen
for it power management. Take a look at the SA1100 framebuffer driver from
the arm tree. 
   Second we can use the special handler in fb_info to replace the one in
the console. Since their are devices that have special needs we can't
depend on the default console power management function. 
   You made the point about multiple devices. If you have more than one
card of the same type you can use the same call back function. Just pass
different data (struct fb_info) to the pm_register function. This will
allow for different VTs to blank at different time. No would it not suck
if someone left their VT and when it went blank it blanked your head while
you are working. This prevents that. Yes you have to register for each
device to the power management layer. 
   The next case is same card multiple heads. You can have two cases. The
first case is each head can preform its own power management. Easy, treat 
each card as a seperate device. You need a seperate fb_info for each
framebuffer anyways. The final case is where you have multiple heads but
one card and the power management is shared. Again you don't want your
console to go blank because the other one is not being worked on. Again
easy, share the struct pm_dev between each fb_info struct. Just make sure
you have proper locking in this case.