From 6feeca5cb725e15a7f6ca0d4234e5fb9c4046809 Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Thu, 27 Jan 2022 14:45:59 +0100
Subject: drm/vc4: hdmi: Don't try disabling SCDC on Pi0-3.
Git-commit: 71702c495b78dfbc22eeac32ea9cda452862750d
Patch-mainline: v5.17-rc4
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

The code that set the scdc_enabled flag to ensure it was
disabled at boot time also ran on Pi0-3 where there is no
SCDC support. This lead to a warning in vc4_hdmi_encoder_post_crtc_disable
due to vc4_hdmi_disable_scrambling being called and trying to
read (and write) register HDMI_SCRAMBLER_CTL which doesn't
exist on those platforms.

Only set the flag should the interface be configured to support
more than HDMI 1.4.

Fixes: 1998646129fa ("drm/vc4: hdmi: Introduce a scdc_enabled flag")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220127134559.292778-1-maxime@cerno.tech
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 3286decf5be5..6d5a6388ca1e 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -2510,7 +2510,8 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 	 * vc4_hdmi_disable_scrambling() will thus run at boot, make
 	 * sure it's disabled, and avoid any inconsistency.
 	 */
-	vc4_hdmi->scdc_enabled = true;
+	if (variant->max_pixel_clock > HDMI_14_MAX_TMDS_CLK)
+		vc4_hdmi->scdc_enabled = true;
 
 	ret = variant->init_resources(vc4_hdmi);
 	if (ret)
-- 
2.38.1