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Date: Fri, 22 Aug 2025 15:34:29 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Stanislav Fomichev <stfomichev@gmail.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com,
 pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org,
 almasrymina@google.com, sdf@fomichev.me, joe@dama.to,
 linux-kselftest@vger.kernel.org
Subject: Re: [PATCH net-next 4/4] selftests: drv-net: ncdevmem: configure
 and restore HDS threshold
Message-ID: <20250822153429.4e6829b4@kernel.org>
In-Reply-To: <aKjunRT-rmsd8tLH@mini-arch>
References: <20250822200052.1675613-1-kuba@kernel.org>
	<20250822200052.1675613-5-kuba@kernel.org>
	<aKjunRT-rmsd8tLH@mini-arch>
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On Fri, 22 Aug 2025 15:26:37 -0700 Stanislav Fomichev wrote:
> > @@ -436,8 +490,14 @@ static int configure_headersplit(bool on)
> >  
> >  	req = ethtool_rings_set_req_alloc();
> >  	ethtool_rings_set_req_set_header_dev_index(req, ifindex);
> > -	/* 0 - off, 1 - auto, 2 - on */
> > -	ethtool_rings_set_req_set_tcp_data_split(req, on ? 2 : 0);
> > +	if (on) {
> > +		ethtool_rings_set_req_set_tcp_data_split(req,
> > +						ETHTOOL_TCP_DATA_SPLIT_ENABLED);
> > +		ethtool_rings_set_req_set_hds_thresh(req, 0);  
> 
> From talking to Taehee awhile ago it seemed like unconditionally
> setting 0 will fail on the devices that don't support it.
> Is it not the case anymore with ethnl_set_rings_validate?

Good point! ring params are validated against the supported attr flags.
We can pass in config here and only set hds_thresh if max was reported.
That should mean driver supports the setting.