Re: i945G 1280x768 sync polarity bug

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Tim Roberts wrote:
Barry Scott wrote:

Using the Xfree86 4.6.0 i810 driver I'm seeing a problem with sync
polarity setting.

This modeline is required for 1280x768 mode:

Modeline "1280x768"   79.30  1280 1335 1473 1665  768 769 772 793
-hsync +vsync

But the syncs, as shown on an oscilloscope are +hsync +vsync.


Does this matter any more?  I thought the relevance of sync polarity
ended in the middle of the Clinton administration.
Good question. We note that the EDID data wants these sync polarities.
Does the monitor use the pulse widths or the polarity to tell one mode
from another? We think that the polarity is used, but we are far from
certain.

Looking at the VBE code it seems that as long as the Flags are
defined correctly by the driver then its down to the INT10 BIOS
to set the syncs on the hardware.

Do you think this is a BIOS bug or a driver bug?


It may be an expectations bug.  As you note, the Intel driver, like the
Savage driver, relies on the BIOS to set the mode.  The BIOS has a
limited set of video modes, with canned parameters for each timing.  It
is not infinitely variable.  If the BIOS thinks 1280x768 should have
positive syncs, then you are going to get positive syncs
I'm using 915resolution to add 1280x768 and 1360x768 into the BIOS.

It seems that if there is an entry in the BIOS for 1280x768 then the driver
is happy to to call INT10 to pass in the timings and sync polarity data.

If as you say the BIOS timings are the only ones used then what is the point
of the INT10 call to pass in the timings?

Barry

_______________________________________________

Devel@xxxxxxxxxxx
http://XFree86.Org/mailman/listinfo/devel

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [X Forum]     [XFree86]     [XFree86 Newbie]     [X.Org]     [IETF Annouce]     [Security]     [Fontconfig]     [Bugtraq]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]

  Powered by Linux