linux-kernel - [PATCH] drm/panthor: Fix NULL pointer dereference on panthor_fw

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Message-ID: <20251215203312.1084182-1-karunika.choo@arm.com>
Date: Mon, 15 Dec 2025 20:33:12 +0000
From: Karunika Choo <karunika.choo@....com>
To: dri-devel@...ts.freedesktop.org
Cc: nd@....com,
	Boris Brezillon <boris.brezillon@...labora.com>,
	Steven Price <steven.price@....com>,
	Liviu Dudau <liviu.dudau@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	linux-kernel@...r.kernel.org,
	aishwarya.tcv@....com
Subject: [PATCH] drm/panthor: Fix NULL pointer dereference on panthor_fw_unplug

This patch removes the MCU halt and wait for halt procedures during
panthor_fw_unplug() as the MCU can be in a variety of states or the FW
may not even be loaded/initialized at all, the latter of which can lead
to a NULL pointer dereference.

It should be safe on unplug to just disable the MCU without waiting for
it to halt as it may not be able to.

Fixes: 514072549865 ("drm/panthor: Support GLB_REQ.STATE field for Mali-G1 GPUs")
Suggested-by: Boris Brezillon <boris.brezillon@...labora.com>
Signed-off-by: Karunika Choo <karunika.choo@....com>
---
 drivers/gpu/drm/panthor/panthor_fw.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index 4beaa589ba66..a64ec8756bed 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -1261,10 +1261,6 @@ void panthor_fw_unplug(struct panthor_device *ptdev)
 		if (ptdev->fw->irq.irq)
 			panthor_job_irq_suspend(&ptdev->fw->irq);
 
-		panthor_fw_halt_mcu(ptdev);
-		if (!panthor_fw_wait_mcu_halted(ptdev))
-			drm_warn(&ptdev->base, "Failed to halt MCU on unplug");
-
 		panthor_fw_stop(ptdev);
 	}
 
-- 
2.49.0