[Bug 109267] [GLK DSI] Display not working with i915 driver

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=109267

--- Comment #63 from Stanislav Lisovskiy <stanislav.lisovskiy at intel.com> ---
(In reply to Mark Wynn Garcia from comment #62)
> Created attachment 144151 [details]
> dmesg-max-cdclk
> 
> So I tried something, which is to modify the patch and max the cdclk to
> 316800. It actually completely removed all flicker/modesetting that happens
> when starting X11. It also reduced flickering to just once instance in
> between grub and boot.
> 
> Right now I really want to know what will happen if we can remove that
> modeset on boot, that maybe at least we will preserve working states even if
> there is still a bug in i915's initialization routines for GLK. In the
> attached dmesg, I think these are what's triggering the modeset:
> 
> [    4.941737] [drm:pipe_config_err [i915]] mismatch in
> base.adjusted_mode.crtc_vtotal (expected 1334, found 1335)
> [    4.941786] [drm:pipe_config_err [i915]] mismatch in
> base.adjusted_mode.crtc_vblank_end (expected 1334, found 1335)
> [    4.941834] [drm:pipe_config_err [i915]] mismatch in dsi_pll.ctrl
> (expected 0x00000132, found 0x00000532)
> 
> I'll try hacking around this one, and if you any ideas, if you think this is
> a good direction to pursue, please let me know.

I don't think those pipe config mismatches are triggering a modeset: those are
just warnings when sw calculated and hw configs do not match(which happens
quite often to be honest and often doesn't affect anything). Those checks are
happening before modeset, which is triggered by userspace and just give
warnings. 

You said you see some flickering, but do you see actual picture?

In your last log I also saw couple of weird modesets, when userspace tries to
set 1366x768 resulution, while using fb of size 800x1200, which makes
atomic_check and thus modesetting fail:

[    4.923785] [drm:drm_atomic_check_only [drm]] checking 000000008bb8c67f
[    4.923802] [drm:drm_atomic_check_only [drm]] [PLANE:62:plane 1B] invalid
source coordinates 1366.000000x768.000000+0.000000+0.000000 (fb 800x1280)
[    4.923816] [drm:drm_atomic_check_only [drm]] [PLANE:62:plane 1B] atomic
core check failed

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