On Wed, Jan 13, 2021 at 3:30 AM Jon Hunter <jonathanh@xxxxxxxxxx> wrote: > > > On 18/12/2020 03:16, Saravana Kannan wrote: > > As discussed in LPC 2020, cyclic dependencies in firmware that couldn't > > be broken using logic was one of the last remaining reasons > > fw_devlink=on couldn't be set by default. > > > > This series changes fw_devlink so that when a cyclic dependency is found > > in firmware, the links between those devices fallback to permissive mode > > behavior. This way, the rest of the system still benefits from > > fw_devlink, but the ambiguous cases fallback to permissive mode. > > > > Setting fw_devlink=on by default brings a bunch of benefits (currently, > > only for systems with device tree firmware): > > * Significantly cuts down deferred probes. > > * Device probe is effectively attempted in graph order. > > * Makes it much easier to load drivers as modules without having to > > worry about functional dependencies between modules (depmod is still > > needed for symbol dependencies). > > > One issue we have come across with this is the of_mdio.c driver. On > Tegra194 Jetson Xavier I am seeing the following ... > > boot: logs: [ 4.194791] WARNING KERN WARNING: CPU: 0 PID: 1 at /dvs/git/dirty/git-master_l4t-upstream/kernel/drivers/base/core.c:1189 device_links_driver_bound+0x240/0x260 > boot: logs: [ 4.207683] WARNING KERN Modules linked in: > boot: logs: [ 4.210691] WARNING KERN CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.11.0-rc3-next-20210112-gdf869cab4b35 #1 > boot: logs: [ 4.219221] WARNING KERN Hardware name: NVIDIA Jetson AGX Xavier Developer Kit (DT) > boot: logs: [ 4.225628] WARNING KERN pstate: 80400009 (Nzcv daif +PAN -UAO -TCO BTYPE=--) > boot: logs: [ 4.231542] WARNING KERN pc : device_links_driver_bound+0x240/0x260 > boot: logs: [ 4.236587] WARNING KERN lr : device_links_driver_bound+0xf8/0x260 > boot: logs: [ 4.241560] WARNING KERN sp : ffff800011f4b980 > boot: logs: [ 4.244819] WARNING KERN x29: ffff800011f4b980 x28: ffff00008208a0a0 > boot: logs: [ 4.250051] WARNING KERN x27: ffff00008208a080 x26: 00000000ffffffff > boot: logs: [ 4.255271] WARNING KERN x25: 0000000000000003 x24: ffff800011b99000 > boot: logs: [ 4.260489] WARNING KERN x23: 0000000000000001 x22: ffff800011df14f0 > boot: logs: [ 4.265706] WARNING KERN x21: ffff800011f4b9f8 x20: ffff800011df1000 > boot: logs: [ 4.270934] WARNING KERN x19: ffff00008208a000 x18: 0000000000000005 > boot: logs: [ 4.276166] WARNING KERN x17: 0000000000000007 x16: 0000000000000001 > boot: logs: [ 4.281382] WARNING KERN x15: ffff000080030c90 x14: ffff0000805c9df8 > boot: logs: [ 4.286618] WARNING KERN x13: 0000000000000000 x12: ffff000080030c90 > boot: logs: [ 4.291847] WARNING KERN x11: ffff0000805c9da8 x10: 0000000000000040 > boot: logs: [ 4.297061] WARNING KERN x9 : ffff000080030c98 x8 : 0000000000000000 > boot: logs: [ 4.302291] WARNING KERN x7 : 0000000000000009 x6 : 0000000000000000 > boot: logs: [ 4.307509] WARNING KERN x5 : ffff000080100000 x4 : 0000000000000000 > boot: logs: [ 4.312739] WARNING KERN x3 : ffff800011df1e38 x2 : ffff000080908c10 > boot: logs: [ 4.317956] WARNING KERN x1 : 0000000000000001 x0 : ffff0000809ca400 > boot: logs: [ 4.323183] WARNING KERN Call trace: > boot: logs: [ 4.325593] WARNING KERN device_links_driver_bound+0x240/0x260 > boot: logs: [ 4.330301] WARNING KERN driver_bound+0x70/0xd0 > boot: logs: [ 4.333740] WARNING KERN device_bind_driver+0x50/0x60 > boot: logs: [ 4.337671] WARNING KERN phy_attach_direct+0x258/0x2e0 > boot: logs: [ 4.341718] WARNING KERN phylink_of_phy_connect+0x7c/0x140 > boot: logs: [ 4.346081] WARNING KERN stmmac_open+0xb04/0xc70 > boot: logs: [ 4.349612] WARNING KERN __dev_open+0xe0/0x190 > boot: logs: [ 4.352972] WARNING KERN __dev_change_flags+0x16c/0x1b8 > boot: logs: [ 4.357081] WARNING KERN dev_change_flags+0x20/0x60 > boot: logs: [ 4.360856] WARNING KERN ip_auto_config+0x2a0/0xfe8 > boot: logs: [ 4.364633] WARNING KERN do_one_initcall+0x58/0x1b8 > boot: logs: [ 4.368405] WARNING KERN kernel_init_freeable+0x1ec/0x240 > boot: logs: [ 4.372698] WARNING KERN kernel_init+0x10/0x110 > boot: logs: [ 4.376130] WARNING KERN ret_from_fork+0x10/0x18 > > > So looking at this change does this mean that the of_mdio needs to be > converted to a proper driver? Sorry, there's not enough context in this log for me to tell how this is even related to of_mdio.c. My guess is this is related to network stack directly calling device_bind_driver() and not updating device link state correctly. See what device_links_check_suppliers() does in the normal path. I think I know which warning this is, but can you check your tree and tell me the code you see in drivers/base/core.c:1189 ? Also, can you give me a few more lines above and below this log and also explain why you think this is related to of_mdio.c? Where is the DT file for this board in case I need to look at it? And where is this phy node defined in DT? If there's an easy way to convert it to a proper driver, that's always better than calling into driver core in a piecemeal fashion. > I would have thought that this will be > seen on several platforms. I'm surprised you are seeing this issue only now. I'd have expected it to have happened even without this series. -Saravana
