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Re: [RFC PATCH v2 6/8] pci/arm: don't do iommu call for phantom functions


  • To: Jan Beulich <jbeulich@xxxxxxxx>
  • From: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
  • Date: Thu, 18 May 2023 17:05:40 -0400
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  • Cc: Paul Durrant <paul@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Rahul Singh <rahul.singh@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, "Bertrand Marquis" <bertrand.marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Thu, 18 May 2023 21:06:02 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 5/12/23 03:28, Jan Beulich wrote:
> On 11.05.2023 21:16, Stewart Hildebrand wrote:
>> It's not necessary to add/remove/assign/deassign pci phantom functions
>> for the ARM SMMU drivers. All associated AXI stream IDs are added during
>> the iommu call for the base PCI device/function.
>>
>> However, the ARM SMMU drivers can cope with the extra/unnecessary calls just
>> fine, so this patch is RFC as it's not strictly required.
> 
> Tying the skipping to IS_ENABLED(CONFIG_HAS_DEVICE_TREE) goes against
> one of Julien's earlier comments, towards DT and ACPI wanting to
> co-exist at some point. So I think keeping the supposedly unnecessary
> calls is going to be unavoidable, unless you have a runtime property
> that you could check instead.

I'll drop this patch in v3



 


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