1 files changed, 39 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-6.1/950-0950-drm-vc4-hdmi-Avoid-hang-with-debug-registers-when-su.patch b/target/linux/bcm27xx/patches-6.1/950-0950-drm-vc4-hdmi-Avoid-hang-with-debug-registers-when-su.patch
new file mode 100644
index 0000000000..8e36b79794
--- /dev/null
+++ b/target/linux/bcm27xx/patches-6.1/950-0950-drm-vc4-hdmi-Avoid-hang-with-debug-registers-when-su.patch
@@ -0,0 +1,39 @@
+From e5e7679d634b10e88df340c85cd8368c9f9989eb Mon Sep 17 00:00:00 2001
+From: Dom Cobley <popcornmix@gmail.com>
+Date: Tue, 5 Sep 2023 19:38:24 +0100
+Subject: [PATCH] drm/vc4: hdmi: Avoid hang with debug registers when suspended
+
+Trying to read /sys/kernel/debug/dri/1/hdmi1_regs
+when the hdmi is disconnected results in a fatal system hang.
+
+This is due to the pm suspend code disabling the dvp clock.
+That is just a gate of the 108MHz clock in DVP_HT_RPI_MISC_CONFIG,
+which results in accesses hanging AXI bus.
+
+Protect against this.
+
+Signed-off-by: Dom Cobley <popcornmix@gmail.com>
+---
+ drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
++++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
+@@ -193,6 +193,8 @@ static int vc4_hdmi_debugfs_regs(struct
+ 	if (!drm_dev_enter(drm, &idx))
+ 		return -ENODEV;
+ 
++	WARN_ON(pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev));
++
+ 	drm_print_regset32(&p, &vc4_hdmi->hdmi_regset);
+ 	drm_print_regset32(&p, &vc4_hdmi->hd_regset);
+ 	drm_print_regset32(&p, &vc4_hdmi->cec_regset);
+@@ -202,6 +204,8 @@ static int vc4_hdmi_debugfs_regs(struct
+ 	drm_print_regset32(&p, &vc4_hdmi->ram_regset);
+ 	drm_print_regset32(&p, &vc4_hdmi->rm_regset);
+ 
++	pm_runtime_put(&vc4_hdmi->pdev->dev);
++
+ 	drm_dev_exit(idx);
+ 
+ 	return 0;