Bug#422430: Information from a modified fbdev_modes_equal
On Wed, 2008-02-13 at 14:51 -0600, Bill Gatliff wrote:
>
> I googled around and found this bug report after getting hit with the
> "FBIOPUT_VSCREENINFO succeeded but modified mode" error.
[...]
> My target is an IMX27ADS (arm) board, running sid. A day later :), the output:
[...]
> sync 2013265921 1
[...]
> So on my platform, the difference is in the sync value. Not quite sure
> what that value is,
It's the horizontal / vertical sync flags, see FB_SYNC_*
in /usr/include/linux/fb.h .
> and still tracking down whether the fb driver in the kernel is
> supposed to be setting it or not. Or whether the logic in
> fbdev_modes_equal() should be looking at it at all.
I think it should - if the kernel framebuffer device modifies the sync
flags, it's effectively a different mode than the one the X server wants
- this can make the difference between a mode working or not on a given
monitor.
Also, the high bits it sets aren't defined in /usr/include/linux/fb.h,
so I suspect this is really a bug in the kernel framebuffer device.
--
Earthling Michel Dänzer | http://tungstengraphics.com
Libre software enthusiast | Debian, X and DRI developer
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