Created attachment 18032 [details]
Xorg.0.log_20080731_master_git.log

Created attachment 18033 [details]
Xorg.0.log_intel_2_4_0.log

Created attachment 18034 [details]
Xorg.0.log_intel_2_3_2.log

Created attachment 18035 [details]
xrandr_20080731_master_git.txt

Created attachment 18036 [details]
xrandr_intel_2_3_2.txt

bisecting reveals:

45c1da56891723dd85153853885dd3b52a23c117 is first bad commit
commit 45c1da56891723dd85153853885dd3b52a23c117
Author: Hong Liu <hong.liu@intel.com>
Date:   Fri Jun 20 10:57:14 2008 +0800

    Fix SDVO HDMI output.
    
    While some cards had enough initialized at startup to work already, others
    required that the driver actually initialize the required AVI info frame.
    (cherry picked from commit 05df8c0b31721a9ccc7215fb1cda1115758367c7)

--

One more note: If the xserver is started with a bad driver once, then restarting xserver with a good driver will also display no image. You need to reboot the entire machine to get SDVO HDMI output working again.

Thanks for the bisecting.
It's interesting:
In 2.3.x, we don't have HDMI support, but your machine works.
Hong added the patch into 2.4.0, which makes many people's SDVO-HDMI working (including ours, all are Asus P5E-VM G35 HDMI board), but it makes your machine not work now.

Reassign back to Zhenyu, as Zhenyu has taken this over from Hong.

Does it work if you comment out these two lines?

In src/i830_sdvo.c, i830_sdvo_mode_set() function.

    if (dev_priv->encode.hdmi_rev) 
        i830_sdvo_set_avi_infoframe(output, mode);

No it does NOT work.

But it works if I comment out these lines:

In src/i830_sdvo.c, i830_sdvo_init() function.

	if (dev_priv->encode.hdmi_rev != 0) {
	    /* enable hdmi encoding mode if supported */
	    i830_sdvo_set_encode(output, SDVO_ENCODE_HDMI);
	    i830_sdvo_set_colorimetry(output, SDVO_COLORIMETRY_RGB256);
	    name_prefix = "HDMI";
	}

It also works if I just force SDVO_ENCODE_DVI:

diff --git a/src/i830_sdvo.c b/src/i830_sdvo.c
index d9b76d4..9c4d11c 100644
--- a/src/i830_sdvo.c
+++ b/src/i830_sdvo.c
@@ -1845,7 +1845,7 @@ i830_sdvo_init(ScrnInfoPtr pScrn, int output_device)
        i830_sdvo_get_supp_encode(output, &dev_priv->encode);
        if (dev_priv->encode.hdmi_rev != 0) {
            /* enable hdmi encoding mode if supported */
-           i830_sdvo_set_encode(output, SDVO_ENCODE_HDMI);
+           i830_sdvo_set_encode(output, SDVO_ENCODE_DVI);
            i830_sdvo_set_colorimetry(output, SDVO_COLORIMETRY_RGB256);
            name_prefix = "HDMI";
        }

Basically I'm connecting a DVI display (by means of an HDMI/DVI adapter) as you can see from my first post. I don't have a real home entertainment HDMI device such as a TV with HDMI input to cross check.

Since neither SDVO information is available to the public
http://softwarecommunity.intel.com/isn/Community/en-US/forums/thread/28280007.aspx

nor any technical datasheet for the Silicon Image 174 HDMI Transmitter, I really don't know what's the correct transmission mode in this setup.

If DVI displays have to be treated special, then I'd guess you'll find the information that it's a DVI device in some EDID extension.

It looks like
VESA Display Information Extension Block Standard (DI-EXT) page 14
http://www.vesa.org/Public/EDID%20EXTENSIONS/DIEXT.pdf

contains the information: Offset 02h

"02h" --- Digital Visual Interface (DVI) -- Single Link
"05h" --- Digital Visual Interface (DVI) -- For Consumer Electronics

Created attachment 18134 [details] [review]
sdvo hdmi mode test

Could you try this patch to see if driver can correctly detect encoding mode?

Current xserver might lack support for EDID extension, should be added soon.

Yes this patch works for me. Tested with both:

xf86-video-intel-2.4-branch f3b72c59e5000bcdb07cbdf080e09c55b9826eff
master                      1a59cc6b9acf312de1755d67757bf7f1967342e4

Thanks for your quick submission!

Fine. Could you enable ModeDebug option in xorg.conf and send me X log? so I can review what that new encoding mode command gets back from your device.

Created attachment 18135 [details]
Xorg.0.log with ModeDebug and patch applied

what's the log file type? seems not text/plain?

it is .gz (19KB) from 240Kb. That's why I had chosen "application/octet-stream" in the first place.

Let me know if I should readd/replace with .txt version.

Got it. It looks "get encode" command really reads back current mode, 00 is DVI mode, 01 is HDMI mode.

Thanks for test, I'll push this fix to upstream soon.

Created attachment 18148 [details] [review]
updated sdvo hdmi mode detect patch

Could you help to verify this updated patch? I've tested with a HDMI TV and a HDMI-DVI monitor.

The updated hdmi mode detect patch works also fine here on DVI display.

Patch is pushed, so close.