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Message-ID: <aTFQv157O-wJjVrZ@gaggiata.pivistrello.it>
Date: Thu, 4 Dec 2025 10:13:35 +0100
From: Francesco Dolcini <francesco@...cini.it>
To: Mark Brown <broonie@...nel.org>
Cc: Francesco Dolcini <francesco@...cini.it>,
Siddharth Vadapalli <s-vadapalli@...com>,
Anurag Dutta <a-dutta@...com>, linux-spi@...r.kernel.org,
linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] spi: cadence-quadspi: Fix clock enable underflows due to
runtime PM
Hello Mark,
On Tue, Dec 02, 2025 at 10:53:44PM +0000, Mark Brown wrote:
> The recent refactoring of where runtime PM is enabled done in commit
> f1eb4e792bb1 ("spi: spi-cadence-quadspi: Enable pm runtime earlier to
> avoid imbalance") made the fact that when we do a pm_runtime_disable()
> in the error paths of probe() we can trigger a runtime disable which in
> turn results in duplicate clock disables. Early on in the probe function
> we do a pm_runtime_get_noresume() since the probe function leaves the
> device in a powered up state but in the error path we can't assume that PM
> is enabled so we also manually disable everything, including clocks. This
> means that when runtime PM is active both it and the probe function release
> the same reference to the main clock for the IP, triggering warnings from
> the clock subsystem:
>
> [ 8.693719] clk:75:7 already disabled
> [ 8.693791] WARNING: CPU: 1 PID: 185 at /usr/src/kernel/drivers/clk/clk.c:1188 clk_core_disable+0xa0/0xb
> ...
> [ 8.694261] clk_core_disable+0xa0/0xb4 (P)
> [ 8.694272] clk_disable+0x38/0x60
> [ 8.694283] cqspi_probe+0x7c8/0xc5c [spi_cadence_quadspi]
> [ 8.694309] platform_probe+0x5c/0xa4
>
> Avoid this confused ownership by moving the pm_runtime_get_noresume() to
> after the last point at which the probe() function can fail.
>
> Reported-by: Francesco Dolcini <francesco@...cini.it>
> Closes: https://lore.kernel.org/r/20251201072844.GA6785@francesco-nb
> Signed-off-by: Mark Brown <broonie@...nel.org>
> Cc: stable@...r.kernel.org
Unless I did some stupid mistake testing the patch, it does not fix the issue.
Here the log with v6.18 + this patch
[ 6.347380] ------------[ cut here ]------------
[ 6.352025] clk:75:7 already disabled
[ 6.355727] WARNING: CPU: 2 PID: 180 at drivers/clk/clk.c:1188 clk_core_disable+0xa4/0xac
[ 6.363921] Modules linked in: aes_ce_blk aes_ce_cipher ghash_ce gf128mul snd_soc_simple_card(+)
snd_soc_simple_card_utils spi_cadence_quadspi(+) optee(+) display_connector tee tps65219_pwrbutton u
sb_conn_gpio gpio_keys dwc3_am62 roles k3_j72xx_bandgap ti_ads1015 industrialio_triggered_buffer kfi
fo_buf sa2ul hci_uart sha512 bluetooth rtc_ti_k3 ecdh_generic libsha512 sha256 ecc snd_soc_davinci_m
casp snd_soc_ti_udma rfkill sha1 authenc snd_soc_ti_edma wave5 libaes snd_soc_ti_sdma cdns_dsi cdns_
dphy omap_hwspinlock lm75 omap_mailbox snd_soc_nau8822 i3c ina2xx lontium_lt8912b m_can_platform m_c
an can_dev pwm_tiehrpwm spi_omap2_mcspi fuse ipv6 libsha1 autofs4
[ 6.421984] CPU: 2 UID: 0 PID: 180 Comm: (udev-worker) Not tainted 6.18.0+ #2 PREEMPT
[ 6.429902] Hardware name: Toradex Verdin AM62P WB on Verdin Development Board (DT)
[ 6.437555] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 6.444515] pc : clk_core_disable+0xa4/0xac
[ 6.448708] lr : clk_core_disable+0xa4/0xac
[ 6.452896] sp : ffff800080bd37f0
[ 6.456234] x29: ffff800080bd37f0 x28: 0000000000000000 x27: ffff000001924810
[ 6.463406] x26: ffff000001924810 x25: ffffd9bd273e0408 x24: ffff000001924800
[ 6.470554] x23: 0000000000000000 x22: ffff000001439800 x21: 00000000ffffffed
[ 6.477693] x20: ffff000002476c00 x19: ffff000002476c00 x18: 0000000000000006
[ 6.484831] x17: 0000000000000000 x16: ffffd9bd3f665260 x15: 0720072007200720
[ 6.491970] x14: 0720072007200720 x13: 0720072007200720 x12: ffffd9bd401ee538
[ 6.499108] x11: 0000000000000058 x10: 0000000000000018 x9 : ffffd9bd401ee538
[ 6.506242] x8 : 0000000000000194 x7 : ffffd9bd40246538 x6 : ffffd9bd40246538
[ 6.513380] x5 : ffff00007fb886c8 x4 : 0000000000000000 x3 : 0000000000000027
[ 6.520518] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000005504300
[ 6.527656] Call trace:
[ 6.530104] clk_core_disable+0xa4/0xac (P)
[ 6.534296] clk_disable+0x30/0x4c
[ 6.537706] cqspi_probe+0x7c0/0xc64 [spi_cadence_quadspi]
[ 6.543209] platform_probe+0x5c/0xa4
[ 6.546885] really_probe+0xc0/0x39c
[ 6.550467] __driver_probe_device+0x7c/0x14c
[ 6.554831] driver_probe_device+0x3c/0x120
[ 6.559022] __driver_attach+0xc4/0x200
[ 6.559387] lt8912 1-0048: supply vccmipirx not found, using dummy regulator
[ 6.562855] bus_for_each_dev+0x7c/0xdc
[ 6.573734] driver_attach+0x24/0x30
[ 6.577315] bus_add_driver+0x110/0x240
[ 6.581158] driver_register+0x68/0x130
[ 6.585001] __platform_driver_register+0x24/0x30
[ 6.589714] cqspi_platform_driver_init+0x20/0x1000 [spi_cadence_quadspi]
[ 6.596516] do_one_initcall+0x60/0x1e0
[ 6.600363] do_init_module+0x54/0x23c
[ 6.604126] load_module+0x1810/0x1f14
[ 6.607886] init_module_from_file+0x88/0xcc
[ 6.612168] __arm64_sys_finit_module+0x264/0x358
[ 6.616883] invoke_syscall.constprop.0+0x50/0xe0
[ 6.619334] lt8912 1-0048: supply vccsysclk not found, using dummy regulator
[ 6.621583] do_el0_svc+0xa8/0xe0
[ 6.631945] el0_svc+0x3c/0x148
[ 6.635095] el0t_64_sync_handler+0xa0/0xf0
[ 6.639285] el0t_64_sync+0x198/0x19c
[ 6.642955] ---[ end trace 0000000000000000 ]---
[ 6.655277] ------------[ cut here ]------------
[ 6.659991] clk:75:7 already unprepared
[ 6.667941] WARNING: CPU: 2 PID: 180 at drivers/clk/clk.c:1047 clk_core_unprepare+0xe4/0x104
[ 6.668689] lt8912 1-0048: supply vcclvdstx not found, using dummy regulator
[ 6.676411] Modules linked in: spidev evdev(+) rng_core aes_ce_blk aes_ce_cipher ghash_ce gf128mu
l snd_soc_simple_card snd_soc_simple_card_utils spi_cadence_quadspi(+) optee display_connector tee t
ps65219_pwrbutton usb_conn_gpio gpio_keys dwc3_am62 roles k3_j72xx_bandgap ti_ads1015 industrialio_t
riggered_buffer kfifo_buf sa2ul hci_uart sha512 bluetooth rtc_ti_k3 ecdh_generic libsha512 sha256 ec
c snd_soc_davinci_mcasp snd_soc_ti_udma rfkill sha1 authenc snd_soc_ti_edma wave5 libaes snd_soc_ti_
sdma cdns_dsi cdns_dphy omap_hwspinlock lm75 omap_mailbox snd_soc_nau8822 i3c ina2xx lontium_lt8912b
m_can_platform m_can can_dev pwm_tiehrpwm spi_omap2_mcspi fuse ipv6 libsha1 autofs4
[ 6.699332] lt8912 1-0048: supply vcchdmitx not found, using dummy regulator
[ 6.743120] CPU: 2 UID: 0 PID: 180 Comm: (udev-worker) Tainted: G W 6.18.0+ #2 P
REEMPT
[ 6.743139] Tainted: [W]=WARN
[ 6.743142] Hardware name: Toradex Verdin AM62P WB on Verdin Development Board (DT)
[ 6.743147] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 6.743153] pc : clk_core_unprepare+0xe4/0x104
[ 6.743168] lr : clk_core_unprepare+0xe4/0x104
[ 6.743175] sp : ffff800080bd37f0
[ 6.743178] x29: ffff800080bd37f0 x28: 0000000000000000 x27: ffff000001924810
[ 6.796577] x26: ffff000001924810 x25: ffffd9bd273e0408 x24: ffff000001924800
[ 6.799311] lt8912 1-0048: supply vcclvdspll not found, using dummy regulator
[ 6.803704] x23: 0000000000000000 x22: ffff000001439800 x21: 00000000ffffffed
[ 6.803713] x20: 0000000000000000 x19: ffff000002476c00 x18: 0000000000000000
[ 6.803723] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[ 6.803731] x14: 000000000000008f x13: 00000000efe4b99a x12: 00009b471872c248
[ 6.803740] x11: 00000000000000c0 x10: 00000000000009e0 x9 : ffff800080bd3660
[ 6.803749] x8 : ffff000005504d40 x7 : 000000000000b67e x6 : 000000000000ba61
[ 6.803758] x5 : 0000000078b6e217 x4 : 0000000000000818 x3 : 0000000000800000
[ 6.803767] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000005504300
[ 6.803777] Call trace:
[ 6.803781] clk_core_unprepare+0xe4/0x104 (P)
[ 6.825908] lt8912 1-0048: supply vcchdmipll not found, using dummy regulator
[ 6.832255] clk_unprepare+0x2c/0x44
[ 6.832266] cqspi_probe+0x7c8/0xc64 [spi_cadence_quadspi]
[ 6.832286] platform_probe+0x5c/0xa4
[ 6.894596] really_probe+0xc0/0x39c
[ 6.898176] __driver_probe_device+0x7c/0x14c
[ 6.902534] driver_probe_device+0x3c/0x120
[ 6.906715] __driver_attach+0xc4/0x200
[ 6.910548] bus_for_each_dev+0x7c/0xdc
[ 6.914380] driver_attach+0x24/0x30
[ 6.917954] bus_add_driver+0x110/0x240
[ 6.921789] driver_register+0x68/0x130
[ 6.925627] __platform_driver_register+0x24/0x30
[ 6.930333] cqspi_platform_driver_init+0x20/0x1000 [spi_cadence_quadspi]
[ 6.937128] do_one_initcall+0x60/0x1e0
[ 6.940968] do_init_module+0x54/0x23c
[ 6.944720] load_module+0x1810/0x1f14
[ 6.948471] init_module_from_file+0x88/0xcc
[ 6.952740] __arm64_sys_finit_module+0x264/0x358
[ 6.957445] invoke_syscall.constprop.0+0x50/0xe0
[ 6.962149] do_el0_svc+0xa8/0xe0
[ 6.965463] el0_svc+0x3c/0x148
[ 6.968605] el0t_64_sync_handler+0xa0/0xf0
[ 6.972785] el0t_64_sync+0x198/0x19c
[ 6.976447] ---[ end trace 0000000000000000 ]---
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