FAILED: patch "[PATCH] drm/rockchip: psr: do not dereference encoder before it is" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4eda776c3cefcb1f01b2d85bd8753f67606282b5 Mon Sep 17 00:00:00 2001
From: Enric Balletbo i Serra <[email protected]>
Date: Sat, 13 Oct 2018 12:56:54 +0200
Subject: [PATCH] drm/rockchip: psr: do not dereference encoder before it is
null checked.

'encoder' is dereferenced before it is null sanity checked, hence we potentially have a null pointer dereference bug. Instead, initialise drm_drv from encoder->dev->dev_private after we are sure 'encoder' is not null.

index 79d00d861a31..01ff3c858875 100644
@@ -189,12 +189,14 @@ EXPORT_SYMBOL(rockchip_drm_psr_flush_all);
 int rockchip_drm_psr_register(struct drm_encoder *encoder,
 			int (*psr_set)(struct drm_encoder *, bool enable))
 {
-	struct rockchip_drm_private *drm_drv = encoder->dev->dev_private;
+	struct rockchip_drm_private *drm_drv;
 	struct psr_drv *psr;
 
 	if (!encoder || !psr_set)
 		return -EINVAL;
 
+	drm_drv = encoder->dev->dev_private;
+
 	psr = kzalloc(sizeof(struct psr_drv), GFP_KERNEL);
 	if (!psr)
 		return -ENOMEM;