Re: Driver for Sharp LH155BA

Re: Driver for Sharp LH155BA

[Richard Wolf]

 

> -----Original Message-----
> From: linux-fbdev-devel-bounces@lists.sourceforge.net 
> [mailto:linux-fbdev-devel-bounces@lists.sourceforge.net] On 
> Behalf Of Markus Schorer
> Sent: Tuesday, 1 August 2006 4:58 PM
> To: linux-fbdev-devel@lists.sourceforge.net
> Subject: Re: [Linux-fbdev-devel] Driver for Sharp LH155BA
> 
> Antonino A. Daplas wrote:
> > Richard Wolf wrote:
> >> Presumably if I take the shadow buffer route then I could maintain 
> >> _two_ shadow buffers.  This would allow me to detect 
> whether the user 
> >> accessible buffer had been changed and update the display 
> only when necessary.
> > 
> > Yes, that will work too.
> > 
> 
> check for the epson SED15xx (not sure) driver. sounds like 
> similar hardware, same approach.
> 
> markus
> --

Excellent, thanks.

Richard

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Multihead support

[Sean D'Epagnier]

I think multihead support is slightly broken with fbdev.

I have multihead working with nvidiafb and matroxfb. I had to patch the
kernel to get console text to update on the non-active vt.

In userspace programs, I know how to  register signal handlers to notify
a program when it gains or loses the active vt, but I don't think there is
a way to correctly detect when a framebuffer device becomes visible or
hidden.   The FBIOGET_CON2FBMAP ioctl provides a means to find which 
fbdev devices is mapped to a given console, but as far as I know to do
the reverse lookup (find the vt attached to a given fbdev) can't be done.
There are really 3 states a vt can be in:
1. active/visible
2. inactive/visible   (only applies to multihead)
3. inactive/invisible

If it were possible to register a signal handler for visible changes the
same way as active changes, this would fix the problem.

Xorg for example won't run on /dev/fb0 and allow me to run something else
on /dev/fb1  I have in my own programs written hacks to poll con2fb, at
a timed interval.  This is a terrible solution, and it has a high probability
of corrupting the screen output (until refresh)

I think in the future this will be come a bigger concern as x11 is slowly
being separated from the hardware, and it will become useful to run
multiple sessions of x11.  I would like to discuss all possible solutions,
and hopefully implement a simple working solution.


Thanks,
Sean D'Epagnier

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