[PATCH] drm/i915: Fixup legacy plane->crtc link for initial fb config

[Daniel Vetter]

This is a very similar bug in the load detect code fixed in

commit 9128b040eb774e04bc23777b005ace2b66ab2a85
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Tue Mar 3 17:31:21 2015 +0100

    drm/i915: Fix modeset state confusion in the load detect code

But this time around it was the initial fb code that forgot to update
the plane->crtc pointer. Otherwise it's the exact same bug, with the
exact same restrains (any set_config call/ioctl that doesn't disable
the pipe papers over the bug for free, so fairly hard to hit in normal
testing). So if you want the full explanation just go read that one
over there - it's rather long ...

Cc: Matt Roper <matthew.d.roper at intel.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Josh Boyer <jwboyer at fedoraproject.org>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
This is the version for -next. The one for -fixes just needs an
s/primary/intel_crtc->base.primary/ and some fudge in the diff. I just
want to apply this in both trees since with all the cherry-picking the
conflicts are fun already and with this patch in both places we can
just go with the code in -next.

Cheers, Daniel
---
 drivers/gpu/drm/i915/intel_display.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ceb2e61b4c91..cb508542c6ab 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2594,6 +2594,7 @@ intel_find_plane_obj(struct intel_crtc *intel_crtc,
 
 		primary->fb = &plane_config->fb->base;
 		primary->state->crtc = &intel_crtc->base;
+		primary->crtc = &intel_crtc->base;
 		update_state_fb(primary);
 
 		return;
@@ -2627,6 +2628,7 @@ intel_find_plane_obj(struct intel_crtc *intel_crtc,
 			drm_framebuffer_reference(c->primary->fb);
 			primary->fb = c->primary->fb;
 			primary->state->crtc = &intel_crtc->base;
+			primary->crtc = &intel_crtc->base;
 			update_state_fb(intel_crtc->base.primary);
 			obj->frontbuffer_bits |= INTEL_FRONTBUFFER_PRIMARY(intel_crtc->pipe);
 			break;
-- 
2.1.4