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From: John Garry <john.garry@huawei.com>
To: Will Deacon <will@kernel.org>
Cc: "Isaac J. Manjarres" <isaacm@codeaurora.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Saravana Kannan <saravanak@google.com>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Bjorn Helgaas <bhelgaas@google.com>,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v2 6/9] Revert "iommu/arm-smmu: Make arm-smmu-v3 explicitly non-modular"
Date: Fri, 8 Nov 2019 17:25:09 +0000
Message-ID: <c4cb13d3-3786-2e45-ba57-9965cead9a49@huawei.com> (raw)
In-Reply-To: <20191108164728.GB20866@willie-the-truck>

On 08/11/2019 16:47, Will Deacon wrote:
> On Fri, Nov 08, 2019 at 04:44:25PM +0000, John Garry wrote:
>> On 08/11/2019 16:17, John Garry wrote:
>>> 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@ubuntu:/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);
>>>> +
>>
>> BTW, it now looks like it was your v1 series I was testing there, on your
>> branch iommu/module. It would be helpful to update for ease of testing.
> 

Hi Will,

> Yes, sorry about that. I'll update it now (although I'm not sure it will
> help with this -- I was going to see what happens with other devices such
> as the intel-iommu or storage controllers)

So I tried your v2 series for this - it has the same issue, as I 
anticipated.

It seems that some iommu drivers do call iommu_device_register(), so 
maybe a decent reference. Or simply stop the driver being unbound.

Cheers,
John

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Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-08 15:15 [PATCH v2 0/9] iommu: Permit modular builds of ARM SMMU[v3] drivers Will Deacon
2019-11-08 15:16 ` [PATCH v2 1/9] drivers/iommu: Export core IOMMU API symbols to permit modular drivers Will Deacon
2019-11-08 15:16 ` [PATCH v2 2/9] iommu/of: Request ACS from the PCI core when configuring IOMMU linkage Will Deacon
2019-11-08 15:16 ` [PATCH v2 3/9] PCI: Export pci_ats_disabled() as a GPL symbol to modules Will Deacon
2019-11-08 15:16 ` [PATCH v2 4/9] drivers/iommu: Take a ref to the IOMMU driver prior to ->add_device() Will Deacon
2019-11-08 15:16 ` [PATCH v2 5/9] iommu/of: Take a ref to the IOMMU driver during ->of_xlate() Will Deacon
2019-11-08 15:16 ` [PATCH v2 6/9] Revert "iommu/arm-smmu: Make arm-smmu-v3 explicitly non-modular" Will Deacon
2019-11-08 16:17   ` John Garry
2019-11-08 16:44     ` John Garry
2019-11-08 16:47       ` Will Deacon
2019-11-08 17:25         ` John Garry [this message]
2019-11-08 17:32           ` Will Deacon
2019-11-08 17:48             ` Will Deacon
2019-11-08 18:00               ` John Garry
2019-11-08 17:49             ` John Garry
2019-11-08 15:16 ` [PATCH v2 7/9] iommu/arm-smmu-v3: Allow building as a module Will Deacon
2019-11-08 15:16 ` [PATCH v2 8/9] Revert "iommu/arm-smmu: Make arm-smmu explicitly non-modular" Will Deacon
2019-11-08 15:16 ` [PATCH v2 9/9] iommu/arm-smmu: Allow building as a module Will Deacon

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