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Florian Fainelli says: ==================== Rework GENET MDIO controller clocking 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. Changes in v2: - added missing ret assignment in the if (IS_ERR(priv->clk)) branch - added Jacob's R-by tags - corrected the commit ID being reverted in patch #3 ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.