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From: Jan Blunck <jblunck@infradead.org>
Date: Fri, 23 Dec 2016 11:27:33 +0100
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To: Thomas Monjalon <thomas.monjalon@6wind.com>
Cc: dev@dpdk.org, Shreyansh Jain <shreyansh.jain@nxp.com>,
David Marchand <david.marchand@6wind.com>,
Stephen Hemminger <stephen@networkplumber.org>
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Subject: Re: [dpdk-dev] [PATCH v4 18/23] ethdev: Helper to map to struct
rte_pci_device
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On Fri, Dec 23, 2016 at 9:30 AM, Thomas Monjalon
<thomas.monjalon@6wind.com> wrote:
> 2016-12-22 19:13, Jan Blunck:
>> On Thu, Dec 22, 2016 at 4:21 PM, Thomas Monjalon
>> <thomas.monjalon@6wind.com> wrote:
>> > 2016-12-21 16:09, Jan Blunck:
>> >> PCI drivers could use this helper instead of directly accessing fields of
>> >> rte_eth_dev to map to rte_pci_device.
>> > [...]
>> >> +/**
>> >> + * @internal
>> >> + * Helper for drivers that need to convert from rte_eth_dev to rte_pci_device.
>> >> + */
>> >> +static inline struct rte_pci_device *__attribute__((always_inline))
>> >> +rte_eth_dev_to_pci(struct rte_eth_dev *eth_dev)
>> >> +{
>> >> + return eth_dev->pci_dev;
>> >> +}
>> >
>> > Why adding this function instead of just using DEV_PCI_DEV(eth_dev->device)?
>> >
>> > I think we must try to avoid any PCI (or other bus) reference inside ethdev.h.
>>
>> David requested to move it from rte_pci.h to rte_ethdev.h.
>>
>> It could get forward declared here if one doesn't use it. On the other
>> hand the rte_pci.h would be required to include rte_ethdev.h if we
>> move it.
>
> I think there is a misunderstanding.
> I was just suggesting to drop this function.
But that would undo the whole purpose of adding a helper. The purpose
of the helper is to map from ethdev to the low-level rte_pci_device.
If we remove this helper all users still need to know how to map to
the embedded device structure. What you ask for also means that the
patch "ethdev: Decouple struct rte_eth_dev from struct rte_pci_device"
needs to change all users of the DEV_PCI_DEV() instead of changing the
helper introduced in this patch.
Let me summarize the workable options from my perspective:
1. helper macro to map from eth_dev to pci_dev in rte_pci.h
2. helper inline function to map from eth_dev to pci_dev in rte_ethdev.h
3. put helpers into new header file rte_ethdrv.h
I'm still in favor of the first option but David suggested to remove
it from eal. I could also counter the type-safety argument from
Stephen by adding a type check to it.