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Miller" , netdev@vger.kernel.org, linux-parisc@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: tulip: remove redundant assignment to variable new_csr6 Message-ID: <20220125141401.GV1951@kadam> References: <20220123183440.112495-1-colin.i.king@gmail.com> <20220124103038.76f15516@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220124103038.76f15516@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: JNAP275CA0033.ZAFP275.PROD.OUTLOOK.COM (2603:1086:0:4d::14) To MWHPR1001MB2365.namprd10.prod.outlook.com (2603:10b6:301:2d::28) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 6aa0a650-1296-42c0-fcc3-08d9e00cfb2e X-MS-TrafficTypeDiagnostic: CO6PR10MB5475:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:1284; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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The assignment is redundant > > and can be removed. > > > @@ -21,7 +21,7 @@ void pnic_do_nway(struct net_device *dev) > > struct tulip_private *tp = netdev_priv(dev); > > void __iomem *ioaddr = tp->base_addr; > > u32 phy_reg = ioread32(ioaddr + 0xB8); > > - u32 new_csr6 = tp->csr6 & ~0x40C40200; > > + u32 new_csr6; > > > > if (phy_reg & 0x78000000) { /* Ignore baseT4 */ > > if (phy_reg & 0x20000000) dev->if_port = 5; > > I can't say I see what you mean, it's not set in some cases: > > if (tp->medialock) { > } else if (tp->nwayset && (dev->if_port & 1)) { > next_tick = 1*HZ; > } else if (dev->if_port == 0) { > dev->if_port = 3; > iowrite32(0x33, ioaddr + CSR12); > new_csr6 = 0x01860000; > iowrite32(0x1F868, ioaddr + 0xB8); > } else { > dev->if_port = 0; > iowrite32(0x32, ioaddr + CSR12); > new_csr6 = 0x00420000; > iowrite32(0x1F078, ioaddr + 0xB8); > } > if (tp->csr6 != new_csr6) { > tp->csr6 = new_csr6; > > > That said clang doesn't complain so maybe I'm missing something static > analysis had figured out about this code. You're looking at the wrong function. This is pnic_do_nway() and you're looking at pnic_timer(). Of course, Colin's patch assumes the current behavior is correct... I guess the current behavior can't be that terrible since it predates git and no one has complained. drivers/net/ethernet/dec/tulip/pnic.c 19 void pnic_do_nway(struct net_device *dev) 20 { 21 struct tulip_private *tp = netdev_priv(dev); 22 void __iomem *ioaddr = tp->base_addr; 23 u32 phy_reg = ioread32(ioaddr + 0xB8); 24 u32 new_csr6 = tp->csr6 & ~0x40C40200; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 25 26 if (phy_reg & 0x78000000) { /* Ignore baseT4 */ 27 if (phy_reg & 0x20000000) dev->if_port = 5; 28 else if (phy_reg & 0x40000000) dev->if_port = 3; 29 else if (phy_reg & 0x10000000) dev->if_port = 4; 30 else if (phy_reg & 0x08000000) dev->if_port = 0; 31 tp->nwayset = 1; 32 new_csr6 = (dev->if_port & 1) ? 0x01860000 : 0x00420000; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 33 iowrite32(0x32 | (dev->if_port & 1), ioaddr + CSR12); 34 if (dev->if_port & 1) 35 iowrite32(0x1F868, ioaddr + 0xB8); 36 if (phy_reg & 0x30000000) { 37 tp->full_duplex = 1; 38 new_csr6 |= 0x00000200; 39 } 40 if (tulip_debug > 1) 41 netdev_dbg(dev, "PNIC autonegotiated status %08x, %s\n", 42 phy_reg, medianame[dev->if_port]); 43 if (tp->csr6 != new_csr6) { 44 tp->csr6 = new_csr6; 45 /* Restart Tx */ 46 tulip_restart_rxtx(tp); 47 netif_trans_update(dev); 48 } 49 } 50 } regards, dan carpenter