On 2.6.33-rc1 I noticed that the display of my T500 with a G45 reacts very
slowly (you can see the text appearing) and colors take a time to "solidify".
I.e. making a white terminal black takes some seconds.
After some bisecting and guessing I recognized that the problem showed up
Author: Zhao Yakui <email@example.com>
Date: Fri Nov 20 03:24:16 2009 +0000
drm/i915: Enable LVDS downclock feature through EDID.
If more than one mode with the same resolution defined in EDID has different
refresh rate, it is thought that the downclock is found for LVDS.
We will program the different FPx0/1 register so that we can select
between the low and high frequency.
On the g4x platform we will use the CxSR feature to switch the different
refresh rate if the LVDS downclock feature is supported.
Signed-off-by: Zhao Yakui <firstname.lastname@example.org>
Reviewed-by: Jesse Barnes <email@example.com>
Signed-off-by: Eric Anholt <firstname.lastname@example.org>
Setting dev_priv->lvds_downclock_avail = 0 in intel_find_lvds_downclock()
unsurprisingly avoids the issue.
dmesg, lspci -vvv, config can be found in the referenced lk thread.
As requested the rom, xorg log, and dmesg with drm.debug=0x06 is attached.
Created attachment 32322 [details]
xrandr -q --verbose
Created attachment 32323 [details]
Created attachment 32324 [details]
Created attachment 32328 [details] [review]
Use the software method to switch the different refresh rate for LVDS
Will you please try the attach patch on 2.6.33-rc1/rc2 and see whether the issue still exists?
Please add the boot option of "drm.debug=0x06" and attach the output of dmesg after test.
Created attachment 32329 [details]
dmesg output after patch
Looks way much better now!
Their still is a slight "blinking" about every second or so (visible only with a darker background).
I can confirm this issue on my own T500.
The attached patch resolves the update speed issue. However, I experience another issue with the LVDS downclocking that is not resolved by this patch: it causes the backlight (I think) intensity to become inconsistent. It seems that whenever the update frequency changes (is that what this feature does?), the backlight briefly becomes slightly brighter and then quickly goes back to normal.
For example, after staring at a completely unchanging image, starting to move the mouse cursor causes a flash, and another flash about 1 second after the mouse cursor stops moving. The result is extremely distracting.
Can you enter the console mode after adding the boot option of "nomodeset" and attach the output of intel_reg_dumper?
>intel_reg_dumper is available in intel_gpu_tools package. And the intel_gpu_tools can be found in
the release under http://xorg.freedesktop.org/archive/individual/app/ or the latest code at git://anongit.freedesktop.org/git/xorg/app/intel-gpu-tools.
Install it by standard procedure: autogen.sh, configure, make, and make install
will you please attach the output of acpidump on T500 laptop?
Created attachment 32538 [details]
Output of intel_reg_dumper
I checked out latest Linus git (3c8ad49b015), applied the patch from this bug, booted with nomodeset and then ran intel_reg_dumper followed by acpidump.
Created attachment 32539 [details]
Output of acpidump
The following commit is already shipped:
Author: Jesse Barnes <email@example.com>
Date: Thu Jan 14 20:48:02 2010 +0000
drm/i915: disable LVDS downclock by default
So I will lower the priority of this bug.
*** Bug 26037 has been marked as a duplicate of this bug. ***
Should be fixed now that we don't enable this feature by default.