linux-kernel - [PATCH] drm/imagination: Fix kernel crash when hard resetting the GPU

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Message-ID: <20250624-fix-kernel-crash-gpu-hard-reset-v1-1-6d24810d72a6@imgtec.com>
Date: Tue, 24 Jun 2025 15:22:08 +0100
From: Alessio Belle <alessio.belle@...tec.com>
To: Frank Binns <frank.binns@...tec.com>,
        Matt Coster
	<matt.coster@...tec.com>,
        Alexandru Dadu <alexandru.dadu@...tec.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>
CC: <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        "Alessio Belle" <alessio.belle@...tec.com>
Subject: [PATCH] drm/imagination: Fix kernel crash when hard resetting the
 GPU

The GPU hard reset sequence calls pm_runtime_force_suspend() and
pm_runtime_force_resume(), which according to their documentation should
only be used during system-wide PM transitions to sleep states.

The main issue though is that depending on some internal runtime PM
state as seen by pm_runtime_force_suspend() (whether the usage count is
<= 1), pm_runtime_force_resume() might not resume the device unless
needed. If that happens, the runtime PM resume callback
pvr_power_device_resume() is not called, the GPU clocks are not
re-enabled, and the kernel crashes on the next attempt to access GPU
registers as part of the power-on sequence.

Replace calls to pm_runtime_force_suspend() and
pm_runtime_force_resume() with direct calls to the driver's runtime PM
callbacks, pvr_power_device_suspend() and pvr_power_device_resume(),
to ensure clocks are re-enabled and avoid the kernel crash.

Fixes: cc1aeedb98ad ("drm/imagination: Implement firmware infrastructure and META FW support")

Signed-off-by: Alessio Belle <alessio.belle@...tec.com>
---
 drivers/gpu/drm/imagination/pvr_power.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/imagination/pvr_power.c b/drivers/gpu/drm/imagination/pvr_power.c
index 41f5d89e78b854cf6993838868a4416a220b490a..3e349d039fc0c4176b5c4baf009ffa005a2b28d1 100644
--- a/drivers/gpu/drm/imagination/pvr_power.c
+++ b/drivers/gpu/drm/imagination/pvr_power.c
@@ -386,13 +386,13 @@ pvr_power_reset(struct pvr_device *pvr_dev, bool hard_reset)
 		if (!err) {
 			if (hard_reset) {
 				pvr_dev->fw_dev.booted = false;
-				WARN_ON(pm_runtime_force_suspend(from_pvr_device(pvr_dev)->dev));
+				WARN_ON(pvr_power_device_suspend(from_pvr_device(pvr_dev)->dev));

 				err = pvr_fw_hard_reset(pvr_dev);
 				if (err)
 					goto err_device_lost;

-				err = pm_runtime_force_resume(from_pvr_device(pvr_dev)->dev);
+				err = pvr_power_device_resume(from_pvr_device(pvr_dev)->dev);
 				pvr_dev->fw_dev.booted = true;
 				if (err)
 					goto err_device_lost;

---
base-commit: 1a45ef022f0364186d4fb2f4e5255dcae1ff638a
change-id: 20250619-fix-kernel-crash-gpu-hard-reset-1ed31981f8cd

Best regards,
-- 
Alessio Belle <alessio.belle@...tec.com>