gpiod_request causing fault 'Unable to handle kernel paging request at virtual address'

gpiod_request causing fault 'Unable to handle kernel paging request at virtual address'

[Phil Reid]

Problem occurs in function:
'int gpiod_request(struct gpio_desc *desc, const char *label)'
at statement:
gpiod_dbg(desc, "%s: status %d\n", __func__, status);
if debugging is enabled and status indicates an error.

Commenting out the debug statement resolves the error.
In my case status was return -16 (EBUSY) due to my driver not
releasing the gpio on unloading. Fixing the driver avoid the fault.
I can submit a patch to fix if given some guidance on what the correct fix is.

Call stack as follows:
[<802dfbb8>] (strnlen) from [<802e1170>] (string+0x40/0x10c)
[<802e1170>] (string) from [<802e2fcc>] (vsnprintf+0x178/0x39c)
[<802e2fcc>] (vsnprintf) from [<802e34e0>] (pointer+0x2f0/0x548)
[<802e34e0>] (pointer) from [<802e2f80>] (vsnprintf+0x12c/0x39c)
[<802e2f80>] (vsnprintf) from [<802e374c>] (vscnprintf+0x14/0x2c)
[<802e374c>] (vscnprintf) from [<8006d9d0>] (vprintk_emit+0xd8/0x558)
[<8006d9d0>] (vprintk_emit) from [<8006dfd4>] (vprintk_default+0x34/0x3c)
[<8006dfd4>] (vprintk_default) from [<800e1284>] (printk+0x88/0x90)
[<800e1284>] (printk) from [<802fffc0>] (__dynamic_pr_debug+0x58/0x68)
[<802fffc0>] (__dynamic_pr_debug) from [<80309380>] (gpiod_request+0xf0/0x180)
[<80309380>] (gpiod_request) from [<803095f4>] (gpiod_get_index+0xd8/0x2fc)
[<803095f4>] (gpiod_get_index) from [<7f043be0>] (emit_gpiod_of_get+0x30/0xe4 [EmitDrv])
[<7f043be0>] (emit_gpiod_of_get [EmitDrv]) from [<7f043d0c>] (emit_gpiod_of_array_get+0x78/0xa0 [EmitDrv])
[<7f043d0c>] (emit_gpiod_of_array_get [EmitDrv]) from [<7f04945c>] (adc_mod_probe+0x128/0x338 [AdcMod])
[<7f04945c>] (adc_mod_probe [AdcMod]) from [<7f043228>] (emit_probe+0x12c/0x224 [EmitDrv])
[<7f043228>] (emit_probe [EmitDrv]) from [<7f043824>] (emit_iio_probe_alloc+0x6c/0xe0 [EmitDrv])
[<7f043824>] (emit_iio_probe_alloc [EmitDrv]) from [<7f04913c>] (adc_mod_drv_probe+0x24/0x28 [AdcMod])
[<7f04913c>] (adc_mod_drv_probe [AdcMod]) from [<80350980>] (platform_drv_probe+0x54/0xb4)
[<80350980>] (platform_drv_probe) from [<8034e754>] (driver_probe_device+0x2ec/0x45c)
[<8034e754>] (driver_probe_device) from [<8034e960>] (__driver_attach+0x9c/0xa0)
[<8034e960>] (__driver_attach) from [<8034c4d8>] (bus_for_each_dev+0x70/0xa4)
[<8034c4d8>] (bus_for_each_dev) from [<8034df98>] (driver_attach+0x2c/0x30)
[<8034df98>] (driver_attach) from [<8034dad0>] (bus_add_driver+0x1c8/0x27c)
[<8034dad0>] (bus_add_driver) from [<8034f4e4>] (driver_register+0x88/0x108)
[<8034f4e4>] (driver_register) from [<803508ac>] (__platform_driver_register+0x64/0x6c)
[<803508ac>] (__platform_driver_register) from [<7f04c048>] (adc_mod_init+0x48/0x6c [AdcMod])
[<7f04c048>] (adc_mod_init [AdcMod]) from [<8000984c>] (do_one_initcall+0xc8/0x200)
[<8000984c>] (do_one_initcall) from [<800e154c>] (do_init_module+0x70/0x1e0)
[<800e154c>] (do_init_module) from [<8009e59c>] (load_module+0x1cb4/0x2170)
[<8009e59c>] (load_module) from [<8009ec64>] (SyS_finit_module+0x8c/0xbc)
[<8009ec64>] (SyS_finit_module) from [<80010800>] (ret_fast_syscall+0x0/0x3c)
Code: e24cb004 e3510000 e241e001 0a000011 (e5d01000)


-- 
Regards
Phil Reid