This patch series reworks the way that we manage the GENET MDIO
controller clocks around I/O accesses. During testing with a fully
modular build where bcmgenet, mdio-bcm-unimac, and the Broadcom PHY
driver (broadcom) are all loaded as modules, with no particular care
being taken to order them to mimize deferred probing the following bus
error was obtained:
[ 4.344831] printk: console [ttyS0] enabled
[ 4.351102] 840d000.serial: ttyS1 at MMIO 0x840d000 (irq = 29, base_baud = 5062500) is a Broadcom BCM7271 UART
[ 4.363110] 840e000.serial: ttyS2 at MMIO 0x840e000 (irq = 30, base_baud = 5062500) is a Broadcom BCM7271 UART
[ 4.387392] iproc-rng200 8402000.rng: hwrng registered
[ 4.398012] Consider using thermal netlink events interface
[ 4.403717] brcmstb_thermal a581500.thermal: registered AVS TMON of-sensor driver
[ 4.440085] bcmgenet 8f00000.ethernet: GENET 5.0 EPHY: 0x0000
[ 4.482526] unimac-mdio unimac-mdio.0: Broadcom UniMAC MDIO bus
[ 4.514019] bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this.
[ 4.551304] SError Interrupt on CPU2, code 0x00000000bf000002 -- SError
[ 4.551324] CPU: 2 PID: 8 Comm: kworker/u8:0 Not tainted 6.1.53-0.1pre-g5a26d98e908c #2
[ 4.551330] Hardware name: BCM972180HB_V20 (DT)
[ 4.551336] Workqueue: events_unbound deferred_probe_work_func
[ 4.551363] pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 4.551368] pc : el1_abort+0x2c/0x58
[ 4.551376] lr : el1_abort+0x20/0x58
[ 4.551379] sp : ffffffc00a383960
[ 4.551380] x29: ffffffc00a383960 x28: ffffff80029fd780 x27: 0000000000000000
[ 4.551385] x26: 0000000000000000 x25: ffffff8002839005 x24: ffffffc00a1f9bd0
[ 4.551390] x23: 0000000040000005 x22: ffffffc000a48084 x21: ffffffc00a3dde14
[ 4.551394] x20: 0000000096000210 x19: ffffffc00a3839a0 x18: 0000000000000579
[ 4.551399] x17: 0000000000000000 x16: 0000000100000000 x15: ffffffc00a3838c0
[ 4.551403] x14: 000000000000000a x13: 6e69622f7273752f x12: 3a6e6962732f7273
[ 4.551408] x11: 752f3a6e69622f3a x10: 6e6962732f3d4854 x9 : ffffffc0086466a8
[ 4.551412] x8 : ffffff80049ee100 x7 : ffffff8003231938 x6 : 0000000000000000
[ 4.551416] x5 : 0000002200000000 x4 : ffffffc00a3839a0 x3 : 0000002000000000
[ 4.551420] x2 : 0000000000000025 x1 : 0000000096000210 x0 : 0000000000000000
[ 4.551429] Kernel panic - not syncing: Asynchronous SError Interrupt
[ 4.551432] CPU: 2 PID: 8 Comm: kworker/u8:0 Not tainted 6.1.53-0.1pre-g5a26d98e908c #2
[ 4.551435] Hardware name: BCM972180HB_V20 (DT)
[ 4.551437] Workqueue: events_unbound deferred_probe_work_func
[ 4.551443] Call trace:
[ 4.551445] dump_backtrace+0xe4/0x124
[ 4.551452] show_stack+0x1c/0x28
[ 4.551455] dump_stack_lvl+0x60/0x78
[ 4.551462] dump_stack+0x14/0x2c
[ 4.551467] panic+0x134/0x304
[ 4.551472] nmi_panic+0x50/0x70
[ 4.551480] arm64_serror_panic+0x70/0x7c
[ 4.551484] do_serror+0x2c/0x5c
[ 4.551487] el1h_64_error_handler+0x2c/0x40
[ 4.551491] el1h_64_error+0x64/0x68
[ 4.551496] el1_abort+0x2c/0x58
[ 4.551499] el1h_64_sync_handler+0x8c/0xb4
[ 4.551502] el1h_64_sync+0x64/0x68
[ 4.551505] unimac_mdio_readl.isra.0+0x4/0xc [mdio_bcm_unimac]
[ 4.551519] __mdiobus_read+0x2c/0x88
[ 4.551526] mdiobus_read+0x40/0x60
[ 4.551530] phy_read+0x18/0x20
[ 4.551534] bcm_phy_config_intr+0x20/0x84
[ 4.551537] phy_disable_interrupts+0x2c/0x3c
[ 4.551543] phy_probe+0x80/0x1b0
[ 4.551545] really_probe+0x1b8/0x390
[ 4.551550] __driver_probe_device+0x134/0x14c
[ 4.551554] driver_probe_device+0x40/0xf8
[ 4.551559] __device_attach_driver+0x108/0x11c
[ 4.551563] bus_for_each_drv+0xa4/0xcc
[ 4.551567] __device_attach+0xdc/0x190
[ 4.551571] device_initial_probe+0x18/0x20
[ 4.551575] bus_probe_device+0x34/0x94
[ 4.551579] deferred_probe_work_func+0xd4/0xe8
[ 4.551583] process_one_work+0x1ac/0x25c
[ 4.551590] worker_thread+0x1f4/0x260
[ 4.551595] kthread+0xc0/0xd0
[ 4.551600] ret_from_fork+0x10/0x20
[ 4.551608] SMP: stopping secondary CPUs
[ 4.551617] Kernel Offset: disabled
[ 4.551619] CPU features: 0x00000,00c00080,0000420b
[ 4.551622] Memory Limit: none
[ 4.833838] ---[ end Kernel panic - not syncing: Asynchronous SError Interrupt ]---
The issue here is that we managed to probe the GENET controller, the
mdio-bcm-unimac MDIO controller, but the PHY was still being held in a
probe deferral state because it depended upon a GPIO controller provider
not loaded yet. As soon as that provider is loaded however, the PHY
continues to probe, tries to disable the interrupts, and this causes a
MDIO transaction. That MDIO transaction requires I/O register accesses
within the GENET's larger block, and since its clocks are turned off,
the CPU gets a bus error signaled as a System Error.
The patch series takes the simplest approach of keeping the clocks
enabled just for the duration of the I/O accesses. This is also
beneficial to other drivers like bcmasp2 which make use of the same MDIO
controller driver.
Florian Fainelli (3):
net: mdio: mdio-bcm-unimac: Manage clock around I/O accesses
net: bcmgenet: Pass "main" clock down to the MDIO driver
Revert "net: bcmgenet: Ensure MDIO unregistration has clocks enabled"
drivers/net/ethernet/broadcom/genet/bcmmii.c | 6 +-
drivers/net/mdio/mdio-bcm-unimac.c | 91 ++++++++++---------
include/linux/platform_data/mdio-bcm-unimac.h | 3 +
3 files changed, 55 insertions(+), 45 deletions(-)
--
2.34.1
This reverts commit eac0aac07f6af47b8ba57c8064bf04ed6df73d1d ("net:
bcmgenet: Ensure MDIO unregistration has clocks enabled"). This is no
longer necessary now that the MDIO bus controller has a clock that it
can manage around the I/O accesses.
Signed-off-by: Florian Fainelli <[email protected]>
---
drivers/net/ethernet/broadcom/genet/bcmmii.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/net/ethernet/broadcom/genet/bcmmii.c b/drivers/net/ethernet/broadcom/genet/bcmmii.c
index 7a21950da77c..9ada89355747 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmmii.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmmii.c
@@ -678,7 +678,5 @@ void bcmgenet_mii_exit(struct net_device *dev)
if (of_phy_is_fixed_link(dn))
of_phy_deregister_fixed_link(dn);
of_node_put(priv->phy_dn);
- clk_prepare_enable(priv->clk);
platform_device_unregister(priv->mii_pdev);
- clk_disable_unprepare(priv->clk);
}
--
2.34.1
On 2/16/2024 10:42 AM, Florian Fainelli wrote:
> This reverts commit eac0aac07f6af47b8ba57c8064bf04ed6df73d1d ("net:
> bcmgenet: Ensure MDIO unregistration has clocks enabled"). This is no
> longer necessary now that the MDIO bus controller has a clock that it
> can manage around the I/O accesses.
>
> Signed-off-by: Florian Fainelli <[email protected]>
> ---
Reviewed-by: Jacob Keller <[email protected]>