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Date:   Thu, 19 Nov 2020 22:43:05 +0100
From:   Michal Kubecek <mkubecek@suse.cz>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Huazhong Tan <tanhuazhong@huawei.com>, davem@davemloft.net,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linuxarm@huawei.com, kuba@kernel.org
Subject: Re: [RFC net-next 1/2] ethtool: add support for controling the type
 of adaptive coalescing
Message-ID: <20201119214305.qjwlg7imqw46bltx@lion.mk-sys.cz>
References: <1605758050-21061-1-git-send-email-tanhuazhong@huawei.com>
 <1605758050-21061-2-git-send-email-tanhuazhong@huawei.com>
 <20201119041557.GR1804098@lunn.ch>
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On Thu, Nov 19, 2020 at 05:15:57AM +0100, Andrew Lunn wrote:
> > diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
> > index e2bf36e..e3458d9 100644
> > --- a/include/uapi/linux/ethtool_netlink.h
> > +++ b/include/uapi/linux/ethtool_netlink.h
> > @@ -366,6 +366,7 @@ enum {
> >  	ETHTOOL_A_COALESCE_TX_USECS_HIGH,		/* u32 */
> >  	ETHTOOL_A_COALESCE_TX_MAX_FRAMES_HIGH,		/* u32 */
> >  	ETHTOOL_A_COALESCE_RATE_SAMPLE_INTERVAL,	/* u32 */
> > +	ETHTOOL_A_COALESCE_USE_DIM,			/* u8 */
> 
> This appears to be a boolean? So /* flag */ would be better. Or do you
> think there is scope for a few different algorithms, and an enum would
> be better. If so, you should add the enum with the two current
> options.

NLA_FLAG would suffice for a read only bool attribute but if the
attribute is expected to be set, we need to distinguish three cases:
set to true, set to false and keep current value. That's why we use
NLA_U8 for read write bool attributes (0 false, anything else true and
attribute not present means leave untouched).

Michal