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To:     "linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>
From:   pgeiem <pgeiem@protonmail.com>
Reply-To: pgeiem <pgeiem@protonmail.com>
Subject: [BUG] leds-pca963x : scheduling while atomic
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List-ID: <linux-leds.vger.kernel.org>
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I have a PCA9633 I2C leds controller with hardware blinking enabled connect=
ed to a STM32MP1. I would like to blink one of the led connected on this co=
ntroller when the system goes in standby (backlight for the wakeup button).

I use a custom trigger which call led_trigger_blink function in pm_suspend.=
 When doing this I get a BUG: scheduling while atomic error message from th=
e kernel. If I replace the call to led_trigger_blink by a call to led_trigg=
er_event(trig, LED_FULL) I have no error and the led is turned ON.

The issue come from the pca963x_blink function when i2c_smbus_read_byte_dat=
a(client, PCA963X_MODE2) function is called. What is really surprising to m=
e is that i2c_smbus_read_byte_data is also called from pca963x_brightness w=
ithout issue this time.

Any idea what may cause such an error ?

Thanks in advance for your help
Patrick

[  306.029144] PM: suspend entry (deep)
[  306.034650] Filesystems sync: 0.001 seconds
[  306.039948] Freezing user space processes ... (elapsed 0.001 seconds) do=
ne.
[  306.048293] OOM killer disabled.
[  306.051469] Freezing remaining freezable tasks ... (elapsed 0.001 second=
s) done.
[  306.060167] printk: Suspending console(s) (use no_console_suspend to deb=
ug)
[  306.069415] BUG: scheduling while atomic: sh/104/0x00000002
[  306.069420] Modules linked in:
[  306.069445] CPU: 1 PID: 104 Comm: sh Tainted: G        W         5.10.10=
-00035-ge3756e37171c-dirty #108
[  306.069450] Hardware name: STM32 (Device Tree Support)
[  306.069490] [<c010d3a4>] (unwind_backtrace) from [<c0109d80>] (show_stac=
k+0x10/0x14)
[  306.069510] [<c0109d80>] (show_stack) from [<c0737424>] (dump_stack+0xc0=
/0xd4)
[  306.069529] [<c0737424>] (dump_stack) from [<c013e1e4>] (__schedule_bug+=
0x70/0x84)
[  306.069549] [<c013e1e4>] (__schedule_bug) from [<c073db30>] (__schedule+=
0x40c/0x51c)
[  306.069567] [<c073db30>] (__schedule) from [<c073dcd0>] (schedule+0x90/0=
x118)
[  306.069587] [<c073dcd0>] (schedule) from [<c0741ba4>] (schedule_timeout+=
0x80/0xfc)
[  306.069607] [<c0741ba4>] (schedule_timeout) from [<c073ea3c>] (wait_for_=
completion_timeout+0x8c/0x104)
[  306.069629] [<c073ea3c>] (wait_for_completion_timeout) from [<c05827b0>]=
 (stm32f7_i2c_smbus_xfer+0x1fc/0x618)
[  306.069649] [<c05827b0>] (stm32f7_i2c_smbus_xfer) from [<c057de70>] (__i=
2c_smbus_xfer+0x110/0x730)
[  306.069666] [<c057de70>] (__i2c_smbus_xfer) from [<c057e508>] (i2c_smbus=
_xfer+0x78/0x110)
[  306.069682] [<c057e508>] (i2c_smbus_xfer) from [<c057e680>] (i2c_smbus_r=
ead_byte_data+0x3c/0x6c)
[  306.069699] [<c057e680>] (i2c_smbus_read_byte_data) from [<c073acf8>] (p=
ca963x_blink_set+0x138/0x234)
[  306.069718] [<c073acf8>] (pca963x_blink_set) from [<c05ae12c>] (led_blin=
k_setup+0x2c/0xd4)
[  306.069737] [<c05ae12c>] (led_blink_setup) from [<c05af49c>] (led_trigge=
r_blink+0x40/0x5c)
[  306.069758] [<c05af49c>] (led_trigger_blink) from [<c05651a4>] (touchkey=
_suspend+0x38/0x64)
[  306.069779] [<c05651a4>] (touchkey_suspend) from [<c0479a4c>] (__device_=
suspend+0xf8/0x36c)
[  306.069798] [<c0479a4c>] (__device_suspend) from [<c047ad64>] (dpm_suspe=
nd+0x108/0x1c8)
[  306.069815] [<c047ad64>] (dpm_suspend) from [<c047b110>] (dpm_suspend_st=
art+0x64/0x6c)
[  306.069834] [<c047b110>] (dpm_suspend_start) from [<c015d8d0>] (suspend_=
devices_and_enter+0x148/0x524)
[  306.069851] [<c015d8d0>] (suspend_devices_and_enter) from [<c015deb8>] (=
pm_suspend+0x20c/0x27c)
[  306.069865] [<c015deb8>] (pm_suspend) from [<c015cbe0>] (state_store+0x6=
8/0xc8)
[  306.069882] [<c015cbe0>] (state_store) from [<c02992a4>] (kernfs_fop_wri=
te+0xf8/0x21c)
[  306.069902] [<c02992a4>] (kernfs_fop_write) from [<c020addc>] (vfs_write=
+0xec/0x44c)
[  306.069919] [<c020addc>] (vfs_write) from [<c020b284>] (ksys_write+0x60/=
0xe4)
[  306.069935] [<c020b284>] (ksys_write) from [<c0100060>] (ret_fast_syscal=
l+0x0/0x54)
[  306.069943] Exception stack(0xc26d9fa8 to 0xc26d9ff0)
[  306.069956] 9fa0:                   00000001 00000000 00000001 000db920 =
00000004 00000000
[  306.069970] 9fc0: 00000001 00000000 b6f04080 00000004 00000004 00000020 =
000d7598 000d749c
[  306.069979] 9fe0: 00000004 bed41810 b6e53087 b6dde766