openwrt/target/linux/bcm27xx/patches-6.6/950-0740-drm-vc4-Free-the-dlist-alloc-immediately-if-it-never.patch

From 4aad27d1201b4dc3974d682ba52eb798bdb557cd Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Wed, 22 Nov 2023 18:36:54 +0000
Subject: [PATCH 0740/1085] drm: vc4: Free the dlist alloc immediately if it
 never hit the hw

atomic_check creates a state, and allocates the dlist memory for
it such that atomic_flush can not fail.

On destroy that dlist allocation was being put in the stale list,
even though it had never been programmed into the hardware,
therefore doing lots of atomic_checks could consume all the dlist
memory and fail.

If the dlist has never been programmed into the hardware, then
free it immediately.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/gpu/drm/vc4/vc4_drv.h | 1 +
 drivers/gpu/drm/vc4/vc4_hvs.c | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -665,6 +665,7 @@ struct vc4_hvs_dlist_allocation {
 	struct drm_mm_node mm_node;
 	unsigned int channel;
 	u8 target_frame_count;
+	bool dlist_programmed;
 };
 
 struct vc4_crtc_state {
--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -700,8 +700,11 @@ void vc4_hvs_mark_dlist_entry_stale(stru
 	 * Kunit tests run with a mock device and we consider any hardware
 	 * access a test failure. Let's free the dlist allocation right away if
 	 * we're running under kunit, we won't risk a dlist corruption anyway.
+	 *
+	 * Likewise if the allocation was only checked and never programmed, we
+	 * can destroy the allocation immediately.
 	 */
-	if (kunit_get_current_test()) {
+	if (kunit_get_current_test() || !alloc->dlist_programmed) {
 		spin_lock_irqsave(&hvs->mm_lock, flags);
 		vc4_hvs_free_dlist_entry_locked(hvs, alloc);
 		spin_unlock_irqrestore(&hvs->mm_lock, flags);
@@ -1198,6 +1201,7 @@ static void vc4_hvs_install_dlist(struct
 		return;
 
 	WARN_ON(!vc4_state->mm);
+	vc4_state->mm->dlist_programmed = true;
 
 	if (vc4->gen >= VC4_GEN_6)
 		HVS_WRITE(SCALER6_DISPX_LPTRS(vc4_state->assigned_channel),