From: Yuval Mintz <Yuval.Mintz@qlogic.com>
To: Salil Mehta <mehta.salil.lnk@gmail.com>,
        Salil Mehta <salil.mehta@huawei.com>,
        David Miller <davem@davemloft.net>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "pawel.moll@arm.com" <pawel.moll@arm.com>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
        "paul.gortmaker@windriver.com" <paul.gortmaker@windriver.com>,
        "ijc+devicetree@hellion.org.uk" <ijc+devicetree@hellion.org.uk>,
        "galak@codeaurora.org" <galak@codeaurora.org>,
        "catalin.marinas@arm.com" <catalin.marinas@arm.com>,
        "will.deacon@arm.com" <will.deacon@arm.com>,
        "arnd@arndb.de" <arnd@arndb.de>,
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	<linux-arm-kernel@lists.infradead.org>,
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Subject: RE: [PATCH V4 net-next 4/5] net:hns: Add support of ethtool TSO set
 option for Hip06 in HNS
Thread-Topic: [PATCH V4 net-next 4/5] net:hns: Add support of ethtool TSO set
 option for Hip06 in HNS
Thread-Index: AQHRI8q+/86f2jNjOEOKhpIJ6D1V/J6n5lJQgA5SI4CAB2DV8A==
Date: Sun, 6 Dec 2015 06:43:12 +0000
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> > Isn't AE_VERSION_1 something fixed once you publish your features?
> > If it can't be changed, why not simply remove the features from
> > `hw_features' instead of having to implement this ndo?
> There could be a case where the feature is supported by the SoC
> and therefore it is already part of the 'hw_features' but it has been
> say DISABLED or ENABLED by ethtool. In such a case, we need to
> make sure we strike off that feature from the 'features' flag.
> 
> Therefore, we need this leg I suppose. Let me know If I am missing
> something here or there is a gap in my understanding.

Look at ethtool_set_features() - if something isn't listed in hw_features,
you're not support to be able to change it.

If you can make a one-time decision when registering the netdevice
whether this feature is supported by HW or not [assuming AE_VERSION_1
is available at that point and can't later change] than it's the better alternative.

Cheers,
Yuval 

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