Backport upstream kernel fixes for sun4i-drm and drm_atomic_helper_connector_hdmi_check()

Firstly, the upstream patch for sun4i-drm ensures the HDMI output is initialized successfully.
Secondly, patching drm_atomic_helper_connector_hdmi_check() avoids a null pointer dereference at shutdown or reboot

patch/kernel/archive/sunxi-6.12/patches.armbian/drv-drm-atomic-helper-null-pointer-fix.patch

@@ -0,0 +1,35 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ryzer58 <ryestar101@gmail.com>
+Date: Mon, 23 Jun 2025 18:19:15 +0100
+Subject: Backport null pointer check to drm HDMI atomic helper function
+ 
+ Backport fix from upstream kernel to address null pointer dereference in drm_atomic_helper_connector_hdmi_check().
+ If these checks are not in place, then drm_default_rgb_quant_range(), called by drm_atomic_helper_connector_hdmi_check() 
+ would dereference the NULL pointer to_match in drm_match_cea_mode().
+
+Signed-off-by: Ryzer58 <ryestar101@gmail.com>
+---
+ drivers/gpu/drm/display/drm_hdmi_state_helper.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+index 936a8f95d80f..15661712d722 100644
+--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
++++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+@@ -500,10 +500,13 @@ int drm_atomic_helper_connector_hdmi_check(struct drm_connector *connector,
+ 		drm_atomic_get_new_connector_state(state, connector);
+ 	const struct drm_display_mode *mode =
+ 		connector_state_get_mode(new_conn_state);
+ 	int ret;
+ 
++	if (!new_conn_state->crtc || !new_conn_state->best_encoder)
++		return 0;
++
+ 	new_conn_state->hdmi.is_limited_range = hdmi_is_limited_range(connector, new_conn_state);
+ 
+ 	ret = hdmi_compute_config(connector, new_conn_state, mode);
+ 	if (ret)
+ 		return ret;
+-- 
+Created with Armbian build tools https://github.com/armbian/build
+

patch/kernel/archive/sunxi-6.12/patches.armbian/drv-drm-sun4i-hdmi-atomic-fix.patch

@@ -0,0 +1,60 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ryzer58 <ryestar101@gmail.com>
+Date: Sun, 8 Jun 2025 22:19:27 +0100
+Subject: Backport DRM atomic check function change from upstream kernel to restore HDMI
+  output functionality
+
+Signed-off-by: Ryzer58 <ryestar101@gmail.com>
+---
+ drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 20 +---------
+ 1 file changed, 1 insertion(+), 19 deletions(-)
+
+diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
+index 6c3862f39c55..5d10b1c54cf9 100644
+--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
++++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
+@@ -197,28 +197,10 @@ sun4i_hdmi_connector_clock_valid(const struct drm_connector *connector,
+ 		return MODE_OK;
+ 
+ 	return MODE_NOCLOCK;
+ }
+ 
+-static int sun4i_hdmi_connector_atomic_check(struct drm_connector *connector,
+-					     struct drm_atomic_state *state)
+-{
+-	struct drm_connector_state *conn_state =
+-		drm_atomic_get_new_connector_state(state, connector);
+-	struct drm_crtc *crtc = conn_state->crtc;
+-	struct drm_crtc_state *crtc_state = crtc->state;
+-	struct drm_display_mode *mode = &crtc_state->adjusted_mode;
+-	enum drm_mode_status status;
+-
+-	status = sun4i_hdmi_connector_clock_valid(connector, mode,
+-						  conn_state->hdmi.tmds_char_rate);
+-	if (status != MODE_OK)
+-		return -EINVAL;
+-
+-	return 0;
+-}
+-
+ static enum drm_mode_status
+ sun4i_hdmi_connector_mode_valid(struct drm_connector *connector,
+ 				struct drm_display_mode *mode)
+ {
+ 	unsigned long long rate = drm_hdmi_compute_mode_clock(mode, 8,
+@@ -278,11 +260,11 @@ static const struct drm_connector_hdmi_funcs sun4i_hdmi_hdmi_connector_funcs = {
+ 	.tmds_char_rate_valid	= sun4i_hdmi_connector_clock_valid,
+ 	.write_infoframe	= sun4i_hdmi_write_infoframe,
+ };
+ 
+ static const struct drm_connector_helper_funcs sun4i_hdmi_connector_helper_funcs = {
+-	.atomic_check	= sun4i_hdmi_connector_atomic_check,
++	.atomic_check	= drm_atomic_helper_connector_hdmi_check,
+ 	.mode_valid	= sun4i_hdmi_connector_mode_valid,
+ 	.get_modes	= sun4i_hdmi_get_modes,
+ };
+ 
+ static enum drm_connector_status
+-- 
+Created with Armbian build tools https://github.com/armbian/build
+

patch/kernel/archive/sunxi-6.12/series.conf

@@ -319,6 +319,8 @@
 	patches.armbian/drv-mmc-host-sunxi-mmc-add-h5-emmc-compatible.patch
 	patches.armbian/drv-pinctrl-sunxi-pinctrl-sun50i-h6.c-GPIO-disable_strict_mode.patch
 	patches.armbian/drv-gpu-drm-sun4i-sun8i_mixer.c-add-h3-mixer1.patch
+	patches.armbian/drv-drm-sun4i-hdmi-atomic-fix.patch
+	patches.armbian/drv-drm-atomic-helper-null-pointer-fix.patch
 	patches.armbian/drv-mtd-nand-raw-nand_ids.c-add-H27UBG8T2BTR-BC-nand.patch
 	patches.armbian/drv-mfd-axp20x-add-sysfs-interface.patch
 	patches.armbian/drv-spi-spidev-Add-armbian-spi-dev-compatible.patch