From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Lunn Subject: Re: [PATCH net-next] net: hns3: Add support to change MTU in hardware & netdev Date: Fri, 18 Aug 2017 18:01:57 +0200 Message-ID: <20170818160157.GB3258@lunn.ch> References: <20170818113558.71928-1-salil.mehta@huawei.com> <20170818133128.GA523@lunn.ch> <20170818150358.GA3258@lunn.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org" , "Zhuangyuzeng (Yisen)" , "lipeng (Y)" , "mehta.salil.lnk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Linuxarm To: Salil Mehta Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org > for example, > file: drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c > static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent) > > netdev->priv_flags |= IFF_UNICAST_FLT; > > + /* MTU range: 81 - 9600 */ > + netdev->min_mtu = 81; > + netdev->max_mtu = MAX_MTU; In this cause, the driver is not using the default values. So it sets them. Anyway, try it. After your alloc_etherdev_mqs(), print the value of min_mtu. It should already be set to MIN_ETH_MTU. > I see. IMHO HNS3 is currently limited by maximum buffer per descriptor > which is 64k. I am sure such frames would get dropped in the hardware > itself and which I guess should be more preferable than dropping in > driver since it saves you some precious cpu cycles? If you hardware handles this, then you don't need to do anything. Andrew -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html