Re: [PATCH v2] lan743x: add virtual PHY for PHY-less devices

From: Sergej Bauer
Date: Fri Jan 22 2021 - 23:03:09 EST

resending answer to all:
On Saturday, January 23, 2021 4:32:38 AM MSK Andrew Lunn wrote:
> > it migth be helpful for developers work on userspace networking tools with
> > PHY-less lan743x
>
> (the interface even could not be brought up)
>
> > of course, there nothing much to do without TP port but the difference is
> > representative.
> >
> > sbauer@metamini ~$ sudo ethtool eth7
> > Settings for eth7:
> > Cannot get device settings: No such device
> >
> > Supports Wake-on: pumbag
> > Wake-on: d
> > Current message level: 0x00000137 (311)
> >
> > drv probe link ifdown ifup tx_queued
> >
> > Link detected: no
> >
> > sbauer@metamini ~$ sudo ifup eth7
> > sbauer@metamini ~$ sudo ethtool eth7
> >
> > Settings for eth7:
> > Supported ports: [ MII ]
> > Supported link modes: 10baseT/Full
> >
> > 100baseT/Full
> > 1000baseT/Full
> >
> > Supported pause frame use: Symmetric Receive-only
> > Supports auto-negotiation: Yes
> > Supported FEC modes: Not reported
> > Advertised link modes: 10baseT/Full
> >
> > 100baseT/Full
> > 1000baseT/Full
> >
> > Advertised pause frame use: Symmetric Receive-only
> > Advertised auto-negotiation: Yes
> > Advertised FEC modes: Not reported
> > Speed: 1000Mb/s
> > Duplex: Full
> > Port: MII
> > PHYAD: 0
> > Transceiver: internal
> > Auto-negotiation: on
> > Supports Wake-on: pumbag
> > Wake-on: d
> > Current message level: 0x00000137 (311)
> >
> > drv probe link ifdown ifup tx_queued
> >
> > Link detected: yes
> >
> > sbauer@metamini ~$ sudo mii-tool -vv eth7
> > Using SIOCGMIIPHY=0x8947
> > eth7: negotiated 1000baseT-FD, link ok
> >
> > registers for MII PHY 0:
> > 5140 512d 7431 0011 4140 4140 000d 0000
> > 0000 0200 7800 0000 0000 0000 0000 2000
> > 0000 0000 0000 0000 0000 0000 0000 0000
> > 0000 0000 0000 0000 0000 0000 0000 0000
> >
> > product info: vendor 1d:0c:40, model 1 rev 1
> > basic mode: loopback, autonegotiation enabled
> > basic status: autonegotiation complete, link ok
> > capabilities: 1000baseT-FD 100baseTx-FD 10baseT-FD
> > advertising: 1000baseT-FD 100baseTx-FD 10baseT-FD
> > link partner: 1000baseT-FD 100baseTx-FD 10baseT-FD
>
> You have not shown anything i cannot do with the ethernet interfaces i
> have in my laptop. And since ethtool is pretty standardized, what
> lan743x offers should be pretty much the same as any 1G Ethernet MAC
> using most 1G PHYs.
>
> Andrew

Andrew, I can reproduce segfault with following changes:
sbauer@metamini ~/devel/kernel-works/net-next.git master$ git diff .
diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/
ethernet/microchip/lan743x_main.c
index 3804310c853a..6e2961f47211 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1001,6 +1001,8 @@ static void lan743x_phy_close(struct lan743x_adapter
*adapter)

phy_stop(netdev->phydev);
phy_disconnect(netdev->phydev);
+ if (phy_is_pseudo_fixed_link(netdev->phydev))
+ fixed_phy_unregister(netdev->phydev);
netdev->phydev = NULL;
}

@@ -1018,9 +1020,21 @@ static int lan743x_phy_open(struct lan743x_adapter
*adapter)
if (!phydev) {
/* try internal phy */
phydev = phy_find_first(adapter->mdiobus);
- if (!phydev)
- goto return_error;
-
+ if (!phydev) {
+ struct fixed_phy_status status = {
+ .link = 1,
+ .speed = SPEED_1000,
+ .duplex = DUPLEX_FULL,
+ .asym_pause = 1,
+ };
+
+ phydev = fixed_phy_register(PHY_POLL, &status, NULL);
+ if (!phydev || IS_ERR(phydev)) {
+ netif_err(adapter, probe, netdev,
+ "Failed to register fixed PHY
device\n");
+ goto return_error;
+ }
+ }
ret = phy_connect_direct(netdev, phydev,
lan743x_phy_link_status_change,
PHY_INTERFACE_MODE_GMII);

sbauer@metamini ~/devel/kernel-works/net-next.git master$ sudo modprobe
lan743x
sbauer@metamini ~/devel/kernel-works/net-next.git master$ sudo ifup eth7
sbauer@metamini ~/devel/kernel-works/net-next.git master$ ethtool eth7
Settings for eth7:
Supported ports: [ TP MII ]
Supported link modes: 1000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Speed: 1000Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Cannot get wake-on-lan settings: Operation not permitted
Current message level: 0x00000137 (311)
drv probe link ifdown ifup tx_queued
Link detected: yes
sbauer@metamini ~/devel/kernel-works/net-next.git master$ sudo ifdown eth7
Killed
---

dmesg:
[ 365.856455] lan743x 0000:06:00.0 eth7: Link is Down
[ 365.856542] BUG: kernel NULL pointer dereference, address: 00000000000003c4
[ 365.856611] #PF: supervisor read access in kernel mode
[ 365.856705] #PF: error_code(0x0000) - not-present page
[ 365.856772] PGD 0 P4D 0
[ 365.856832] Oops: 0000 [#1] SMP NOPTI
[ 365.856898] CPU: 0 PID: 21779 Comm: ip Tainted: G O 5.11.0-
rc4net-next+ #4
[ 365.857018] Hardware name: Gigabyte Technology Co., Ltd. H110-D3/H110-D3-
CF, BIOS F24 04/11/2018
[ 365.857111] RIP: 0010:lan743x_phy_close.isra.26+0x28/0x50 [lan743x]
[ 365.857208] Code: c3 90 0f 1f 44 00 00 53 48 89 fb 48 8b bf 28 08 00 00 e8
ab 3e da ff 48 8b bb 28 08 00 00 e8 bf 67 da ff 48 8b bb 28 08 00 00 <f6> 87 c4
03 00 00 04 75 0d 48 c7 83 28 08 00 00 00 00 00 00 5b c3
[ 365.857332] RSP: 0018:ffffb6560468b508 EFLAGS: 00010246
[ 365.857397] RAX: 0000000000000003 RBX: ffff8cfacbe30000 RCX: 0000000000000000
[ 365.857466] RDX: ffffffffc00ae2d8 RSI: 0000000000000001 RDI: 0000000000000000
[ 365.857537] RBP: 0000000000000008 R08: 0000000000000000 R09: ffffffffb2d6dee0
[ 365.857632] R10: ffff8cfb45f69bff R11: ffff8cfb057c829b R12: ffff8cfacbe308c0
[ 365.857697] R13: ffff8cfacbe310b8 R14: ffff8cfacbe31050 R15: ffff8cfacbe308c0
[ 365.857762] FS: 00007f4318318e40(0000) GS:ffff8cfbf6c00000(0000) knlGS:
0000000000000000
[ 365.857844] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 365.857907] CR2: 00000000000003c4 CR3: 0000000145a80001 CR4:
00000000003706f0
[ 365.857972] Call Trace:
[ 365.858029] lan743x_netdev_close+0x223/0x250 [lan743x]
[ 365.858094] __dev_close_many+0x96/0x100
[ 365.858170] __dev_change_flags+0xdc/0x210
[ 365.858264] dev_change_flags+0x21/0x60
[ 365.858325] do_setlink+0x347/0x10e0
[ 365.858385] ? __nla_validate_parse+0x5f/0xaf0
[ 365.858447] __rtnl_newlink+0x541/0x8d0
[ 365.858508] ? get_page_from_freelist+0x1194/0x1310
[ 365.858574] ? mutex_spin_on_owner+0x5c/0xb0
[ 365.858635] ? __mutex_lock.isra.9+0x46e/0x4b0
[ 365.858696] ? asm_exc_page_fault+0x1e/0x30
[ 365.858757] rtnl_newlink+0x43/0x60
[ 365.858817] rtnetlink_rcv_msg+0x134/0x380
[ 365.858878] ? _cond_resched+0x15/0x30
[ 365.858937] ? kmem_cache_alloc+0x3cf/0x7d0
[ 365.858997] ? rtnl_calcit.isra.38+0x110/0x110
[ 365.859058] netlink_rcv_skb+0x50/0x100
[ 365.859118] netlink_unicast+0x1a5/0x280
[ 365.859178] netlink_sendmsg+0x23d/0x470
[ 365.859237] sock_sendmsg+0x5b/0x60
[ 365.859298] ____sys_sendmsg+0x1ef/0x260
[ 365.859358] ? copy_msghdr_from_user+0x5c/0x90
[ 365.859418] ? mntput_no_expire+0x47/0x240
[ 365.859478] ___sys_sendmsg+0x7c/0xc0
[ 365.859537] ? tomoyo_path_number_perm+0x68/0x1e0
[ 365.859600] ? __sk_destruct+0x129/0x1b0
[ 365.859660] ? var_wake_function+0x20/0x20
[ 365.859720] ? fsnotify_grab_connector+0x46/0x80
[ 365.859782] __sys_sendmsg+0x57/0xa0
[ 365.859841] do_syscall_64+0x33/0x80
[ 365.859900] entry_SYSCALL_64_after_hwframe+0x44/0xa9
---
(gdb) l *lan743x_netdev_close+0x223
0x1f43 is in lan743x_netdev_close (drivers/net/ethernet/microchip//
lan743x_main.c:2521).
2516
2517 lan743x_ptp_close(adapter);
2518
2519 lan743x_phy_close(adapter);
2520
2521 lan743x_mac_close(adapter);
2522
2523 lan743x_intr_close(adapter);
2524
2525 return 0;
(gdb)