[PATCH v2] drm/i915: Fix BUG in i915_gem.c when switch to console

[Xi Ruoyao]

In intel_crtc_page_flip, intel_display.c, the code changed the framebuffer
assigned to plane crtc->primary by

crtc->primary->fb = fb;

However, it forgot to change crtc->primary->state->fb. However, when we
switch to console, some kernel code will read crtc->primary->state->fb
to get the framebuffer assigned to crtc->primaty. Then a framebuffer
object can be unpinned twice and a kernel BUG will be produced in i915_gem.c.

So, update crtc->primary->state->fb in intel_display.c using
drm_atomic_set_fb_for_plane to fix the BUG.

Signed-off-by: Xi Ruoyao <xry111 at outlook.com>
Fixed: Bug 93711 <https://bugzilla.kernel.org/show_bug.cgi?id=93711>
---
 Sorry, the previous patch is mangled by email client, so I am re-sending it.

 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 e730789..97083fd 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -37,6 +37,7 @@
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
 #include "i915_trace.h"
+#include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_crtc_helper.h>
@@ -9816,6 +9817,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 	drm_gem_object_reference(&obj->base);
 
 	crtc->primary->fb = fb;
+	drm_atomic_set_fb_for_plane(crtc->primary->state, fb);
 
 	work->pending_flip_obj = obj;
 
-- 
1.9.1