From adaab9e4d632a97e580871082d193f2cb57d98fa Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <tzimmermann@suse.de>
Date: Wed, 11 May 2022 20:31:25 +0200
Subject: drm/client: Don't add new command-line mode
Git-commit: 0facdaa249c4e97346bc0b49c893e4a1d336b7dd
Patch-mainline: v6.0-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849

Don't add a mode for the kernel's command-line parameters from
within the DRM client code. Doing so can result in an unusable
display. If there's no compatible command-line mode, the client
will use one of the connector's preferred modes.

All mode creation and validation has to be performed by the
connector. When clients run, the connector's fill_modes callback
has already processed the kernel parameters and validated each
mode before adding it. The connector's mode list does not contain
invalid modes.

v2:
	* grammar in commit message (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220511183125.14294-4-tzimmermann@suse.de
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/drm_client_modeset.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index b777faa87f04..48e6ce16439f 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -158,8 +158,7 @@ drm_connector_has_preferred_mode(struct drm_connector *connector, int width, int
 	return NULL;
 }
 
-static struct drm_display_mode *
-drm_connector_pick_cmdline_mode(struct drm_connector *connector)
+static struct drm_display_mode *drm_connector_pick_cmdline_mode(struct drm_connector *connector)
 {
 	struct drm_cmdline_mode *cmdline_mode;
 	struct drm_display_mode *mode;
@@ -180,11 +179,10 @@ drm_connector_pick_cmdline_mode(struct drm_connector *connector)
 	if (cmdline_mode->specified == false)
 		return NULL;
 
-	/* attempt to find a matching mode in the list of modes
-	 *  we have gotten so far, if not add a CVT mode that conforms
+	/*
+	 * Attempt to find a matching mode in the list of modes we
+	 * have gotten so far.
 	 */
-	if (cmdline_mode->rb || cmdline_mode->margins)
-		goto create_mode;
 
 	prefer_non_interlace = !cmdline_mode->interlace;
 again:
@@ -218,12 +216,7 @@ drm_connector_pick_cmdline_mode(struct drm_connector *connector)
 		goto again;
 	}
 
-create_mode:
-	mode = drm_mode_create_from_cmdline_mode(connector->dev, cmdline_mode);
-	if (mode)
-		list_add(&mode->head, &connector->modes);
-
-	return mode;
+	return NULL;
 }
 
 static bool drm_connector_enabled(struct drm_connector *connector, bool strict)
-- 
2.38.1