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Subject: Re: [PATCH 8/9] vfio/pci: export nvlink2 support into vendor vfio_pci
 drivers
To:     Jason Gunthorpe <jgg@nvidia.com>,
        Max Gurtovoy <mgurtovoy@nvidia.com>
Cc:     alex.williamson@redhat.com, cohuck@redhat.com, kvm@vger.kernel.org,
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References: <20210309083357.65467-1-mgurtovoy@nvidia.com>
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 <19e73e58-c7a9-03ce-65a7-50f37d52ca15@ozlabs.ru>
 <8941cf42-0c40-776e-6c02-9227146d3d66@nvidia.com>
 <20210310130246.GW2356281@nvidia.com>
From:   Alexey Kardashevskiy <aik@ozlabs.ru>
Message-ID: <3b772357-7448-5fa7-9ecc-c13c08df95c3@ozlabs.ru>
Date:   Thu, 11 Mar 2021 01:24:47 +1100
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On 11/03/2021 00:02, Jason Gunthorpe wrote:
> On Wed, Mar 10, 2021 at 02:57:57PM +0200, Max Gurtovoy wrote:
> 
>>>> +    .err_handler        = &vfio_pci_core_err_handlers,
>>>> +};
>>>> +
>>>> +#ifdef CONFIG_VFIO_PCI_DRIVER_COMPAT
>>>> +struct pci_driver *get_nvlink2gpu_vfio_pci_driver(struct pci_dev *pdev)
>>>> +{
>>>> +    if (pci_match_id(nvlink2gpu_vfio_pci_driver.id_table, pdev))
>>>> +        return &nvlink2gpu_vfio_pci_driver;
>>>
>>>
>>> Why do we need matching PCI ids here instead of looking at the FDT which
>>> will work better?
>>
>> what is FDT ? any is it better to use it instead of match_id ?
> 
> This is emulating the device_driver match for the pci_driver.


No it is not, it is a device tree info which lets to skip the linux PCI 
discovery part (the firmware does it anyway) but it tells nothing about 
which drivers to bind.


> I don't think we can combine FDT matching with pci_driver, can we?

It is a c function calling another c function, all within vfio-pci, this 
is not called by the generic pci code.


-- 
Alexey