Hi,
Peter Colberg wrote:
> To summarize: The external display connected via DisplayPort works
> fine with Linux 3.1, while, with Linux 3.2, it works with lower
> (non-native) resolutions and fails with the maximum (native)
> resolution.
Please report this upstream, following instructions from [1], and let
us know the bug number so we can track it.
The upstream developers may ask you to bisect to find the specific
patch that introduced the problem. It works like this:
0. Prerequisites:
apt-get install git build-essential
1. Get a copy of the kernel source repository:
git clone \
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
cd linux
Or if you already have a copy, update it:
cd linux
git fetch origin
2. Test v3.2:
git checkout v3.2
cp /boot/config-$(uname -r) .config; # current configuration
make localmodconfig; # optional: minimize configuration
make deb-pkg; # optionally with -j<n> for parallel build
dpkg -i ../<name of package>
reboot
... test test test ...
If it doesn't exhibit the problem, declare victory and we can
try to figure out what Debian-specific patch (unlikely) or
configuration change (more likely) caused it. Otherwise:
3. Test v3.1:
git checkout v3.1
make silentoldconfig; # reuse configuration
make deb-pkg; # maybe with -j4
dpkg -i ../<name of package>
reboot
... test test test ...
Hopefully it does not exhibit the problem.
4. Test a version halfway between:
git bisect start v3.2 v3.1; # checks out a version halfway between to
test
make silentoldconfig; # reuse configuration
make deb-pkg; # maybe with -j4
dpkg -i ../<name of package>
reboot
... test test test ...
git bisect bad; # if it exhibits the problem
git bisect good; # if the external display works fine, after a
# power-cycle and with the right resolution
git bisect skip; # if some other problem makes it hard to test
5. Another version to test will be automatically checked out. So:
make silentoldconfig
make deb-pkg; # maybe with -j4
dpkg -i ../<name of package>
reboot
... test ...
git bisect good/bad/skip
6. Rinse and repeat until bored.
7. After sufficiently many iterations, git will indicate the "first
bad commit" --- hoorah! If bored before then, you can run "git
bisect log" to print information about the versions tested in a
form that will allow someone else to pick up where you left off.
At any step if the gitk package is installed, you can run "git
bisect visualize" to watch the regression range narrowing.
Hope that helps,
Jonathan
[1] http://intellinuxgraphics.org/how_to_report_bug.html
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