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.
I added debug messages to show the Flags used. And here is a section
of the log:
(II) I810(0): Not using built-in mode "1280x1024" (height too large
for virtual size)
(II) I810(0): Not using built-in mode "1360x768" (width too large for
virtual size)
(II) I810(0): Increasing the scanline pitch to allow tiling mode (1280
-> 2048).
(--) I810(0): Virtual size is 1280x768 (pitch 2048)
(**) I810(0): *Built-in mode "1280x768"
(**) I810(0): Built-in mode "1024x768"
(**) I810(0): Built-in mode "800x600"
(**) I810(0): Built-in mode "640x480"
(II) I810(0): Attempting to use 60.06Hz refresh for mode "1280x768" (85a)
(II) I810(0): I830SetModeParameters() Flags pMode->Flags 0x6
block->Flags 0x4
(II) I810(0): Attempting to use 75.08Hz refresh for mode "1024x768" (854)
(II) I810(0): I830SetModeParameters() Flags pMode->Flags 0x5
block->Flags 0x0
(II) I810(0): Attempting to use 75.00Hz refresh for mode "800x600" (852)
(II) I810(0): I830SetModeParameters() Flags pMode->Flags 0x5
block->Flags 0x0
(II) I810(0): Attempting to use 75.00Hz refresh for mode "640x480" (850)
(II) I810(0): I830SetModeParameters() Flags pMode->Flags 0xa
block->Flags 0xc
This shows that the I830SetModeParameters() has the correct values in
but pMode-Flags
and block->Flags.
I have also tested other modes as listed here
Mode Flags Syncs on wire
640x480 0xC -hsync -vsync
800x600 0x0 +hsync +vsync
1024x768 0xC -hsync -vsync
1280x1024 0x0 +hsync +vsync
1280x768 0x4 +hsync +vsync
As you can see all the Syncs track the Flags except 1280x768.
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?
Barry
I've just noticed that the refresh rate is 52.73Hz not 60Hz as expected.
Clearly the mode is not being honored.
Barry
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