Hi

Can you please boot with drm.debug=0xe and attach the output of "dmesg"?

Thanks,
Paulo

Created attachment 93565 [details]
dmesg dump with drm.debug=0xe

Created attachment 93568 [details] [review]
Patch with debugging option

Hi

This patch adds a Kernel command line option that will help us debug the problem.

Please apply the patch, then try booting with:
- i915.edp_delays=0
- i915.edp_delays=1
- i915.edp_delays=2
- i915.edp_delays=3
- i915.edp_delays=4

And please tell us which ones solve the bug for you.

If you discover that i915.edp_delays=4 solves the problem for you, you could also try removing chunks of code that look for "i915.edp_delays == EDP_DELAYS_I915_OLD" until you get a minimal set of checks that are essential to get your Kernel working. But this could easily take you a few hours of debugging :)

Thanks,
Paulo

I applied the patch to drm-intel-next (from Daniels repo).

Unfortunately none of the edp_delays solved the problem. Maybe I should have pointed out that I do get console output while booting but when X starts everything goes black. Backlight is on and can be changed while the screen is black.

Any other ideas?

Hi

I made some slight mistakes on yesterday's patch, and I also forgot to revert
one commit. Can you please test
http://cgit.freedesktop.org/~pzanoni/linux/?h=edp-reverts ? Please _make sure_
you're on the edp-reverts branch, and also please make sure you're using
i915.edp_delays=4 and drm.debug=0xe as the Kernel command line parameter.

After you boot, please also run dmesg | grep "eDP delays" just to make sure
you're using the right option :)

If this works for you, you can try reverting the top commits until it stops
working.

Thanks,
Paulo

Hi Paulo, thanks for looking into this.

I still get a blank screen when trying HEAD at this branch with i915.edp_delays=4 and drm.debug=0xe. dmesg tells me it's active so I got the correct kernel running.

I assume you've reverted the whole series at this stage so there must be something else that changed around eDP. I did a bisect twice on 3.14-rc1 and both pointed to the reported commit. 

/me is scratching my head

Created attachment 93769 [details]
dmesg dump with i915.edp_delays=4 and drm.debug=0xe on HEAD of branch edp_reverts

Patrik, make sure you have

commit ec5e0cfb19e79ce3a87b281ce4c2682eb659fa6e
Author: Imre Deak <imre.deak@intel.com>
Date:   Wed Jan 29 13:25:40 2014 +0200

    drm/i915: fix wait_remaining_ms_from_jiffies

from drm-intel-nightly.

Note the branches have moved to a new repo at fdo: http://cgit.freedesktop.org/drm-intel

Yes I have ec5e0cfb19e79ce3a87b281ce4c2682eb659fa6e

By looking at my dmesg it seems the last VDD change is:
[   12.131461] [drm:edp_panel_vdd_off_sync], Turning eDP VDD off
[   12.131474] [drm:edp_panel_vdd_off_sync], PP_STATUS: 0x80000008 PP_CONTROL: 0xabcd0007

Why off and not on?

(In reply to comment #9)
> Why off and not on?

It's a force VDD bypassing regular panel power sequencing.

Finally had some time to look at this again so I did a new bisect but on the -nightly branch and for some reason I got a new first-bad-commit. Not sure why I saw that other patch on the previous 3-4 bisects. Did the patch order change?

Turned out to be the EDP_FORCE_VDD bit missing in ironlake_edp_panel_off(). I've submitted a patch to intel-gfx that solves this problem.

Thanks
Patrik

Created attachment 94966 [details]
Set EDP_FORCE_VDD bit in

Moving the conversation back here (my bad)...

Chris Wilson wrote:

I'd feel more comfortable with;

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 46d065b..876184f 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1872,9 +1872,11 @@ static void intel_disable_dp(struct intel_encoder *encoder)

        /* Make sure the panel is off before trying to change the mode. But also
         * ensure that we have vdd while we switch off the panel. */
+       edp_panel_vdd_on(intel_dp);
        intel_edp_backlight_off(intel_dp);
        intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
        intel_edp_panel_off(intel_dp);
+       edp_panel_vdd_off(intel_dp, true);

        /* cpu edp my only be disable _after_ the cpu pipe/plane is disabled. */
        if (!(port == PORT_A || IS_VALLEYVIEW(dev)))

Or that vdd_off may have to be post-disable.

Calling vdd_on / vdd_off in intel_disble_dp doesn't fix the problem. I'm attaching the broken and working dmesg (applied on top of drm-intel-nightly). Seems I get an extra call to ironlake_edp_panel_vdd_on() with my patch applied.

Created attachment 94967 [details]
dmesg from broken setup (_vdd_on / _vdd_off in intel_disable_dp)

Created attachment 94968 [details]
dmesg from working setup (EDP_FORCE_VDD in _edp_panel_off)

Correction... I'm obviously doing this on drm-intel-fixes (hence the ironlake_ prefixes).

Patrik, can you try moving the edp_panel_vdd_off() that I added down into intel_post_disable_dp()?

The problem as I see it is the hack is to leave the vdd on virtually forever, which may or may not consume a lot of extra power.

I moved it to the bottom of intel_post_disable_dp() (outside the if-stmt) but that didn't do it either. Not sure at what stage the EDP_FORCE_VDD bit is needed (link training?). Not a VESA member so no docs here.

Thinking about it, I think both patches are required. Definitely we need to or in the bit there as in your patch to preserve the VDD setting during the disable. And I think we also need the explicit VDD frobbing during disable.

Created attachment 95007 [details] [review]
Patch with _vdd_on/_vdd_off wrapped intel_disable_dp and EDP_FORCE_VDD bit cleared

So something like this? Paulo, anything you would like to add? If this is ok I'll resend it to the list.

Patrik: Please reword the commit message to make it clear it's a regression. Usually we go with "This regression has been introduced in <commit citation" in a separate paragraph to really make it stand out. Just process nit from me, thanks for taking care of this issue ;-)

Patch sent with better description of the regression. I forgot to tag it v2 in the patch subject so make sure you pick the right one for -fixes.

Thanks

Hmm, I worry about the interaction of this patch with bug 75401.

Thanks for the report, fixed by
commit 825938307f812c7cbfe064c7884bd8bdb27c2144
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Mon Mar 17 15:20:59 2014 +0200

    Revert "drm/i915: don't touch the VDD when disabling the panel"

Closing resolved+fixed. 2.5 years with no comments.