Re: Xorg dies on my deferred I/O fb driver

[Ico Doornekamp <fbdev@zevv.nl>]

* On 2008-12-17 Geert Uytterhoeven <geert@linux-m68k.org> wrote  :

> On Wed, 17 Dec 2008, Ico Doornekamp wrote:
> > Today I wrote a simple framebuffer driver for a SPI driven LCD display
> > with internal memory, using the deferred I/O framework. The display is
> > capable of grayscale, 384x160 pixels.
> > 
> > My driver resembles the metronomefb driver, and seems to work using
> > write() and mmap() with my own test tools.
> > 
> > The next step would be to run Xorg/fbdev on top, but things don't seem
> > to simple work this way.
> > 
> > Xorg starts and detects te framebuffer driver, but dies with the message
> > 
> >   (EE) FBDEV(0): FBIOPUT_VSCREENINFO succeeded but modified mode
> >   (EE) FBDEV(0): mode initialization failed
> > 
> > I'm kind of stuck here. Any tips on how to solve or debug this one ?
> > 
> > On the bottom of this mail I pasted:
> > 
> > - fbinfo -i output
> > - Xorg log
> > - fb_fix_screeninfoa and fb_var_screeninfo from my driver
> > 
> > Running Xorg 1.4.2 on Linux 2.6.27.4
> 
> I guess your frame buffer device driver supports one single video mode only?

Indeed, good guess.

> There's a bug in Xorg that doesn't like drivers that support one
> single video mode only, and always return that single video mode in
> the FBIOPUT_VSCREENINFO ioctl (cfr. the "FBIOPUT_VSCREENINFO succeeded
> but modified mode" message).
> 
> One fix is to modify your frame buffer device driver to reject all
> modes that are not identical to the single supported mode.

Ok, that's the kind of hint I needed, I'll go steal some code from other
drivers right away.

Thanks,

Ico

-- 
:wq
^X^Cy^K^X^C^C^C^C

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