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Date:   Tue, 22 Dec 2020 11:49:32 -0800
From:   isaacm@codeaurora.org
To:     Robin Murphy <robin.murphy@arm.com>
Cc:     iommu@lists.linux-foundation.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        freedreno@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
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        joro@8bytes.org, kernel-team@android.com, will@kernel.org,
        pdaly@codeaurora.org
Subject: Re: [PATCH v2 3/7] iommu/arm-smmu: Add dependency on io-pgtable
 format modules
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 <3b0c191d-3fd0-73db-c1e3-4a80aa7953d7@arm.com>
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On 2020-12-22 11:27, Robin Murphy wrote:
> On 2020-12-22 00:44, Isaac J. Manjarres wrote:
>> The SMMU driver depends on the availability of the ARM LPAE and
>> ARM V7S io-pgtable format code to work properly. In preparation
> 
> Nit: we don't really depend on v7s - we *can* use it if it's
> available, address constraints are suitable, and the SMMU
> implementation actually supports it (many don't), but we can still
> quite happily not use it even so. LPAE is mandatory in the
> architecture so that's our only hard requirement, embodied in the
> kconfig select.
> 
> This does mean there may technically still be a corner case involving
> ARM_SMMU=y and IO_PGTABLE_ARM_V7S=m, but at worst it's now a runtime
> failure rather than a build error, so unless and until anyone
> demonstrates that it actually matters I don't feel particularly
> inclined to give it much thought.
> 
> Robin.
> 
Okay, I'll fix up the commit message, as well as the code, so that it
only depends on io-pgtable-arm.

Thanks,
Isaac
>> for having the io-pgtable formats as modules, add a "pre"
>> dependency with MODULE_SOFTDEP() to ensure that the io-pgtable
>> format modules are loaded before loading the ARM SMMU driver module.
>> 
>> Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
>> ---
>>   drivers/iommu/arm/arm-smmu/arm-smmu.c | 1 +
>>   1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c 
>> b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> index d8c6bfd..a72649f 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> @@ -2351,3 +2351,4 @@ MODULE_DESCRIPTION("IOMMU API for ARM 
>> architected SMMU implementations");
>>   MODULE_AUTHOR("Will Deacon <will@kernel.org>");
>>   MODULE_ALIAS("platform:arm-smmu");
>>   MODULE_LICENSE("GPL v2");
>> +MODULE_SOFTDEP("pre: io-pgtable-arm io-pgtable-arm-v7s");
>> 
> 
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