On Mon, Jan 24, 2022 at 10:30:38AM -0800, Jakub Kicinski wrote:
> On Sun, 23 Jan 2022 18:34:40 +0000 Colin Ian King wrote:
> > Variable new_csr6 is being initialized with a value that is never
> > read, it is being re-assigned later on. 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
