netdev - Re: [PATCH 5/5] PCI: remove pci_enable

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Message-ID: <1eaa46ad-9890-c738-3a85-6468161284ba@gmail.com>
Date:   Mon, 27 Mar 2017 10:30:46 -0700
From:   David Daney <ddaney.cavm@...il.com>
To:     Christoph Hellwig <hch@....de>
Cc:     bhelgaas@...gle.com, davem@...emloft.net,
        netanel@...apurnalabs.com, jcliburn@...il.com,
        chris.snook@...il.com, sgoutham@...ium.com, rric@...nel.org,
        netdev@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 5/5] PCI: remove pci_enable_msix

On 03/27/2017 10:11 AM, Christoph Hellwig wrote:
> On Mon, Mar 27, 2017 at 09:59:35AM -0700, David Daney wrote:
>> On 03/27/2017 01:29 AM, Christoph Hellwig wrote:
>>> Unused now that all callers switched to pci_alloc_irq_vectors.
>>>
>>
>> And you are aware that the ThunderX GPIO driver that I am attempting to
>> merge uses this interface.
>>
>> If this patch gets merged, should I ask to revert it when the GPIO driver
>> goes in?
>
> No.  You should not use pci_enable_msix in your new driver as I told
> you before.
>
>> You offer no solution for drivers that would benefit from using a sparse
>> sub set of the available MSI-X vectors.
>
> Use pci_enable_msix_{exact,range} for now, as I told you before.
>

That still results in twice as many MSI-X being provisioned than are needed.

For drivers that use a contiguous range of MSI-X, your suggestion is 
usable, but for others you are forcing resources to be wasted.  For what 
end?

David Daney