Bug 77201

Previously reported/discussed at https://bbs.archlinux.org/viewtopic.php?pid=1401270 .

Created attachment 97094 [details]
screenshot excerpt showing the lines in text while everything else is okay

Can you perform a bisection?

Looking at firefox-24 on debian with an 845g under awesome, everything looks ok, even http;//wwww.faz.net/

Please also attach your Xorg.0.log.

Also it would be useful to confirm the bug against xf86-video-intel.git.

Thank you, Chris!

(In reply to comment #3)
> Can you perform a bisection?

Sorry, I have not really a clue what you mean. I am no programmer. Do you mean to find out the code commit date which causes this problem? I do not think so if I would have to compile packes myself I will need to stay at the old version and hope that somebody else solves this problem in the driver. I mentioned between which release versions the bad change seems to happen. It is from .910 to .911.

(In reply to comment #5)
> Also it would be useful to confirm the bug against xf86-video-intel.git.

See above, sorry, I think this is too difficult for me.


Attachments follow. I noticed that it also occurs in Thunderbird.

Created attachment 97140 [details]
Thunderbird 24.4.0 in RSS message view (even in the RSS message list there are blank lines - not shown here)

Created attachment 97141 [details]
screenshot of a search on ixquick.com (as before - on Firefox 28.0)

Created attachment 97142 [details]
Xorg.0.log (private information and input devices removed)

git bisect is a tool to identify a commit that introduces a bug.

Start by cloning the xf86-video-intel.git repository,
$ git clone git://anongit.freedesktop.org/xorg/driver/xf86-video-intel
$ cd xf86-video-intel
$ ./autogen.sh --prefix=/usr
$ make && sudo make install

Next time you update your system pkg, it will overwrite our temporary install. autogen is likely to complain about missing development packages, you will have to query arch how best to install those.

Check that you can reproduce the bug.
$ git bisect start
$ git bisect bad
$ git checkout 2.99.910
$ make && sudo make install

Check that you cannot reproduce the bug
$ git bisect good

git will then select a commit roughly halfway between, you then
$ make && sudo make install

Retest, if the result is good:
$ git bisect good

and if bad (lack of lines being drawn):
$ git bisect bad

Repeat until git announces a winner.

Any luck in compiling xf86-video-intel.git?

Created attachment 97177 [details]
the bisect log when the compile error happened

I had a compile error for 

[142f8461944b294dbc3fb0a7bf607bccf0bccc1f] sna/gen2: Tidy blend factor selection for the source 

Final error was:

make: *** [all] Error 2

See attachment 97177 [details] for the log at this state.

I did a 

git reset --hard HEAD~1

then (according to the man page).

Created attachment 97178 [details]
the bisect log when bisect was finished

After this I could successfully finish the bisecting:

Bisecting: 0 revisions left to test after this (roughly 0 steps)
[142f8461944b294dbc3fb0a7bf607bccf0bccc1f] sna/gen2: Tidy blend factor selection for the source

See attachment 97178 [details] for the log.

Do you need and other information?

just a note: git's bisecting was not that hard. Thanks for the excellent guide! I only had to install the packages git and xorg-server-devel (with arch's pacman).

Created attachment 97184 [details] [review]
Fix CA/a8 blend factors

Thanks, that was very useful.

Can you please apply this patch (git apply < /path/to/download) and give it a quick spin?

I have applied attachment 97184 [details] [review] to the newes git version. It removes the problem of missing lines.

I do not know if it is relevant:  for some reason I get wrong mouse cursors with the latest git version (they show the cursor for the last action - no update, e.g. a waiting clock).

Hmm, still updating here, but 855gm is special...

commit a79eb2e29a158910785580409c51a585f25876a7
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Thu Apr 10 20:41:57 2014 +0100

    sna/gen2: Fix CA/a8 blend factors
    
    This is a revert of
    
    commit 142f8461944b294dbc3fb0a7bf607bccf0bccc1f [2.99.911]
    Author: Chris Wilson <chris@chris-wilson.co.uk>
    Date:   Mon Mar 10 15:20:16 2014 +0000
    
        sna/gen2: Tidy blend factor selection for the source
    
    as that broke glyph rendering in firefox for instance.
    
    Reported-by: Carl Eitsger <4607vrfcr84spd21f08@weg-werf-email.de>
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77201
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Just tested on a 845g (which is different at a hw to the 855gm, but uses the same code path for simplicity). I saw some lag in cursor updates, but it turned out just to be awesome waiting for a timeout before switching back from the clock to the arrow.

Confirm, no blank lines in the current HEAD - 9ae8213. Great!  Set to "fixed" - or is this too early?!

By the way: blank lines also appeared in pidgin (saw them with version e8be2a4) - not only in Mozilla products (does pidgin use a gecko for rendering?.

Regarding the cursors: have opened bug 77351

(In reply to comment #21)
> By the way: blank lines also appeared in pidgin (saw them with version
> e8be2a4) - not only in Mozilla products (does pidgin use a gecko for
> rendering?.

They both use cairo, but in this case it is the actual font and font filtering that was important.