linux-kernel - Re: [PATCH v2 6/9] Revert "iommu/arm-smmu: Make arm-smmu-v3 explicitly non-modular"

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Message-ID: <06dfd385-1af0-3106-4cc5-6a5b8e864759@huawei.com>
Date:   Fri, 8 Nov 2019 16:17:45 +0000
From:   John Garry <john.garry@...wei.com>
To:     Will Deacon <will@...nel.org>, <iommu@...ts.linux-foundation.org>,
        <linux-kernel@...r.kernel.org>
CC:     Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Saravana Kannan" <saravanak@...gle.com>,
        "Isaac J. Manjarres" <isaacm@...eaurora.org>,
        Robin Murphy <robin.murphy@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v2 6/9] Revert "iommu/arm-smmu: Make arm-smmu-v3
 explicitly non-modular"

On 08/11/2019 15:16, Will Deacon wrote:
> +MODULE_DEVICE_TABLE(of, arm_smmu_of_match);

Hi Will,

>   
>   static struct platform_driver arm_smmu_driver = {
>   	.driver	= {
>   		.name		= "arm-smmu-v3",
>   		.of_match_table	= of_match_ptr(arm_smmu_of_match),
> -		.suppress_bind_attrs = true,

Does this mean that we can now manually unbind this driver from the SMMU 
device?

Seems dangerous. Here's what happens for me:

root@...ntu:/sys# cd ./bus/platform/drivers/arm-smmu-v3
ind @ubuntu:/sys/bus/platform/drivers/arm-smmu-v3# echo 
arm-smmu-v3.0.auto > unbind
[   77.580351] hisi_sas_v2_hw HISI0162:01: CQE_AXI_W_ERR (0x800) found!
ho [   78.635473] platform arm-smmu-v3.0.auto: CMD_SYNC timeout at 
0x00000146 [hwprod 0x00000146, hwcons 0x00000000]

>   	},
>   	.probe	= arm_smmu_device_probe,
> +	.remove	= arm_smmu_device_remove,
>   	.shutdown = arm_smmu_device_shutdown,
>   };
> -builtin_platform_driver(arm_smmu_driver);
> +module_platform_driver(arm_smmu_driver);
> +


Thanks,
John