Re:Re: [PATCH] drm/panthor: Fix NULL pointer dereference on panthor_fw_unplug

[Andy Yan]

Hello,

At 2025-12-16 20:51:53, "Liviu Dudau" <liviu.dudau@xxxxxxx> wrote:
>On Mon, Dec 15, 2025 at 08:33:12PM +0000, Karunika Choo wrote:
>> 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@xxxxxxxxxxxxx>
>> Signed-off-by: Karunika Choo <karunika.choo@xxxxxxx>
>
>Reviewed-by: Liviu Dudau <liviu@xxxxxxxxxxx>

  Tested-by: Andy Yan <andyshrk@xxxxxxx>

Hope can be merged in 6.19 release cycle.


>
>Best regards,
>Liviu
>
>> ---
>>  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
>>