FAILED: patch "[PATCH] drm/vmwgfx: Fix crtc's atomic check conditional" 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]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x a60ccade88f926e871a57176e86a34bbf0db0098
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024042353-oversight-despair-5bb8@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

a60ccade88f9 ("drm/vmwgfx: Fix crtc's atomic check conditional") 29b77ad7b9ca ("drm/atomic: Pass the full state to CRTC atomic_check") c489573b5b6c ("Merge drm/drm-next into drm-misc-next")

thanks,

greg k-h

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

From a60ccade88f926e871a57176e86a34bbf0db0098 Mon Sep 17 00:00:00 2001
From: Zack Rusin <[email protected]>
Date: Thu, 11 Apr 2024 22:55:10 -0400
Subject: [PATCH] drm/vmwgfx: Fix crtc's atomic check conditional

The conditional was supposed to prevent enabling of a crtc state without a set primary plane. Accidently it also prevented disabling crtc state with a set primary plane. Neither is correct.

Fix the conditional and just driver-warn when a crtc state has been enabled without a primary plane which will help debug broken userspace.

Fixes IGT's kms_atomic_interruptible and kms_atomic_transition tests.

index cd4925346ed4..84ae4e10a2eb 100644
@@ -933,6 +933,7 @@ int vmw_du_cursor_plane_atomic_check(struct drm_plane *plane,
 int vmw_du_crtc_atomic_check(struct drm_crtc *crtc,
 			     struct drm_atomic_state *state)
 {
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
 	struct drm_crtc_state *new_state = drm_atomic_get_new_crtc_state(state,
 									 crtc);
 	struct vmw_display_unit *du = vmw_crtc_to_du(new_state->crtc);

@@ -940,9 +941,13 @@ int vmw_du_crtc_atomic_check(struct drm_crtc *crtc,
 	bool has_primary = new_state->plane_mask &
 			   drm_plane_mask(crtc->primary);
 
-	/* We always want to have an active plane with an active CRTC */
-	if (has_primary != new_state->enable)
-		return -EINVAL;
+	/*
+	 * This is fine in general, but broken userspace might expect
+	 * some actual rendering so give a clue as why it's blank.
+	 */
+	if (new_state->enable && !has_primary)
+		drm_dbg_driver(&vmw->drm,
+			       "CRTC without a primary plane will be blank.\n");
 
 
 	if (new_state->connector_mask != connector_mask &&