[Bug 51081] [ivb] black screen on return to runlevel 3

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=51081

--- Comment #26 from Alex <alupu01 at gmail.com> ---
(In reply to Jani Nikula from comment #25)
> We never found the root cause here, and also failed to report that we were
> unable to solve the bug. And we've neglected the bug since. Apologies. I'm
> afraid we still don't have a clue, but trying a recent kernel might be worth
> it. We do fix plenty of bugs all the time - it just might be we've fixed the
> issue behind this one without connecting the dots to this bug. Please try a
> recent kernel, thanks.

Hi Jani,
Long time no see.  My, how time flies!

HARDWARE reminder
Motherboard: "ASUS P8H77-I" (with intel H77) and intel i7-3770, 16 GB.
Monitor: ASUS VE258Q, connected via HDMI to motherboard.
SOFTWARE reminder
32-bit, i686 GNU/Linux.  BLFS <www.linuxfromscratch.org>

UPDATE
Kernel: 3.16.3 (latest as of this writing, Sep. 27, 2014 11:30 EST).

There is NO longer hang-up ("black screen") on 'modprobe i915' BUT (see
TEST RESULTS below).

TEST METHODOLOGY
1.  Reboot machine _directly_ to Level 3 ("console/text mode").
 Note:  NEVER go to Level 5 (Xorg 7.7) during the procedure below.
        Just stay on the original Level 3.

2.  Based on a trick devised sometime ago while grappling with a
similar(?) problem of changed-screen-resolution (from default 25 rows to 30) on
returning from Level 5 (graphics mode) to Level 3.

The trick:  change to an appropriate font type (lat4a-19) to restore the
25 rows on a _full_ screen.  The resulting text is not as sharp as the original
kernel console type but hey, let's not be too demanding, we're still only 2014!

3.  Legend for the following (hopefully) self-explanatory console text,
 "$" = console root prompt.

TEST RESULTS
After reboot:
$

$ stty -a | grep speed
speed 38400 baud; rows 25; columns 80; ... 

$ lsmod | grep 915

$ modprobe i915                  # No black screen but see next 'stty' results

$ lsmod | grep 915
i915                  553907  1
cfbfillrect             2426  1 i915
cfbimgblt               1687  1 i915
i2c_algo_bit            3687  1 i915
cfbcopyarea             2318  1 i915
drm_kms_helper         24092  1 i915
drm                   161309  3 i915,drm_kms_helper
i2c_core               13418  4 drm,i915,drm_kms_helper,i2c_algo_bit
intel_gtt               8490  1 i915
video                  10362  1 i915
backlight               3705  2 i915,video
button                  3206  1 i915

$ stty -a | grep speed
speed 38400 baud; rows 30; columns 80; line = 0;

$ INITTY=/dev/tty[1-6] ; \
 for TTY in $INITTY ; do setfont lat4a-19 -C $TTY ; done

$ stty -a | grep speed
speed 38400 baud; rows 25; columns 80; line = 0;

CONCLUSION
The situation is much better but still not what I expect:

There should be no change to screen resolution on loading i915.

Thanks,
-- Alex

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