--- /dev/null
+From c2957d7709a43c81e5345d537feaa6980ffcc1a4 Mon Sep 17 00:00:00 2001
+From: James Hughes <james.hughes@raspberrypi.org>
+Date: Mon, 29 Jul 2019 12:02:59 +0100
+Subject: [PATCH] Fixup FKMS interrupt handing for non-existent display
+
+If an errant interrupt flag was received from a non-existent display,
+a NULL pointer access was made. Protect against this by checking if a
+second display is present prior to checking the interrupt flags.
+---
+ drivers/gpu/drm/vc4/vc4_firmware_kms.c | 17 ++++++++++-------
+ 1 file changed, 10 insertions(+), 7 deletions(-)
+
+--- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
++++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
+@@ -1056,14 +1056,17 @@ static irqreturn_t vc4_crtc_irq_handler(
+ vc4_crtc_handle_page_flip(crtc_list[0]);
+ }
+
+- /* Check for the secondary display too */
+- chan = readl(crtc_list[0]->regs + SMIDSW1);
++ if (crtc_list[1]) {
++ /* Check for the secondary display too */
++ chan = readl(crtc_list[0]->regs + SMIDSW1);
+
+- if (chan & 1) {
+- writel(SMI_NEW, crtc_list[0]->regs + SMIDSW1);
+- if (crtc_list[1]->vblank_enabled)
+- drm_crtc_handle_vblank(&crtc_list[1]->base);
+- vc4_crtc_handle_page_flip(crtc_list[1]);
++ if (chan & 1) {
++ writel(SMI_NEW, crtc_list[0]->regs + SMIDSW1);
++
++ if (crtc_list[1]->vblank_enabled)
++ drm_crtc_handle_vblank(&crtc_list[1]->base);
++ vc4_crtc_handle_page_flip(crtc_list[1]);
++ }
+ }
+ }
+