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List:       freedesktop-xorg
Subject:    Re: Problem with xorg-server and s3c2410fb driver
From:       Vasily Khoruzhick <anarsoul () gmail ! com>
Date:       2010-07-26 13:45:04
Message-ID: 201007261645.13393.anarsoul () gmail ! com
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В сообщении от 25 июля 2010 09:35:45 автор Vasily Khoruzhick написал:
> Hi,
> 
> I'm trying to get xorg-server + xf86-video-fbdev working on my device, and
> I'm hitting problem:
> 
> pixclock value of fb mode on my device is 260000 picosecs, and due to
> picosecs <-> khz conversions in xorg-server I'm getting rounding error:
> 
> 1000000000 / 260000 = 3846
> 1000000000 / 3846 = 260010
> 
> (Look through xfree2fbdev_timing and fbdev2xfree_timing functions in
> fbdevhw.c for more details)
> 
> xorg-server gets mode via FBOIGET_VSCREENINFO (pixclock = 260000), converts
> it to its own format, then converts it back to fbmode (due to rounding
> error pixclock - 260010) and then tries to set mode with pixvalue 260010
> via FBIOPUT_VSCREENINFO ioctl, but driver sets it back to 260000, and
> xorg-server fails to startup with this message:
> 
> (EE) FBDEV(0): FBIOPUT_VSCREENINFO succeeded but modified mode.
> 
> With this patch:
> https://svn.pardus.org.tr/pardus/playground/memre/arm/repos/cortex-
> a8/x11/server/xorg-server/files/oe/hack-fbdev-ignore-return-mode.patch
> xorg- server starts with no problem, but it's ugly hack.
> 
> Is there any sane solution to fix my problem?

Any suggestions? It should be common problem for all FB drivers if pixclock 
conversion causes rounding error.

Regards
Vasily

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