linux-kernel - Re: [PATCH V4 11/26] iommu/amd: deprecate pci_get_bus_and

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Date:   Thu, 4 Jan 2018 11:25:46 -0600
From:   Gary R Hook <gary.hook@....com>
To:     Sinan Kaya <okaya@...eaurora.org>, linux-pci@...r.kernel.org,
        timur@...eaurora.org
Cc:     linux-arm-msm@...r.kernel.org,
        "open list:AMD IOMMU (AMD-VI)" <iommu@...ts.linux-foundation.org>,
        linux-arm-kernel@...ts.infradead.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V4 11/26] iommu/amd: deprecate pci_get_bus_and_slot()

On 01/04/2018 10:32 AM, Sinan Kaya wrote:
> On 1/4/2018 11:28 AM, Gary R Hook wrote:
>> On 01/04/2018 06:25 AM, Sinan Kaya wrote:
>>> On 12/19/2017 12:37 AM, Sinan Kaya wrote:
>>>> pci_get_bus_and_slot() is restrictive such that it assumes domain=0 as
>>>> where a PCI device is present. This restricts the device drivers to be
>>>> reused for other domain numbers.
>>>>
>>>> Getting ready to remove pci_get_bus_and_slot() function in favor of
>>>> pci_get_domain_bus_and_slot().
>>>>
>>>> Hard-code the domain number as 0 for the AMD IOMMU driver.
>>
>> <snip>
>>
>>>
>>> Any comments from the IOMMU people?
>>>
>>
>> pci_get_bus_and_slot() appears to (now) be a convenience function that wraps pci_get_domain_bus_and_slot() while using a 0 for the domain value. Exactly what you are doing here, albeit in a more overt way.
>>
>> How is this patch advantageous? Seems to me that if other domains need to be enabled, that driver could be changed if and when that requirement arises.
>>
>> But perhaps I'm missing a nuance here.
>>
>>
> 
> The benefit of the change was discussed here:
> 
> https://lkml.org/lkml/2017/12/19/349
> 
> I hope it helps.
> 
> 

Thank you for pointing out that thread directly. I read through it and 
thought further about this change.

I am not the maintainer, but as an AMD developer, this is fine change. I 
can't ACK but I can agree.

Gary