Re: [PATCH v2.5/3] iommu/arm-smmu-v3: Undo SMMU enable on probe failure

[Robin Murphy <robin.murphy@arm.com>]

On 12/11/2024 3:57 pm, Will Deacon wrote:
> On Tue, Nov 12, 2024 at 02:49:59PM +0000, Robin Murphy wrote:
>> If SMMU probe fails afer arm_smmu_device_reset(), we leave the SMMU
>> enabled with an empty Stream Table, silently blocking all DMA. This
>> proves rather annoying for debugging said probe failure, so let's handle
>> it a bit better by putting the SMMU back into (more or less) the same
>> state as if it hadn't probed at all.
>>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> ---
>>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> index 7908fca962fe..566d66e9c91e 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> @@ -4640,6 +4640,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
>>   	iommu_device_sysfs_remove(&smmu->iommu);
>>   free_iopf:
>>   	iopf_queue_free(smmu->evtq.iopf);
>> +	arm_smmu_device_disable(smmu);
>>   	return ret;
>>   }
> 
> Heh, this is starting to look an awful lot like arm_smmu_device_remove()...

Indeed, functionally that's rather the point; implementation-wise, you 
know I'd branch straight into the middle of a different function if the 
language let me :)

Robin.