记录：外扩GPIOD访问报警告

rk提供的rfkill-bt.c驱动访问外扩GPIO输出如下警告：

[    4.694993] ------------[ cut here ]------------
[    4.694994] WARNING: CPU: 7 PID: 582 at drivers/gpio/gpiolib.c:2805 gpiod_get_raw_value+0x58/0xd4
[    4.695003] Modules linked in:
[    4.695006] CPU: 7 PID: 582 Comm: systemd-rfkill Not tainted 6.1.75 #41
[    4.695008] Hardware name: Rockchip RK3588 Board (DT)
[    4.695010] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    4.695012] pc : gpiod_get_raw_value+0x58/0xd4
[    4.695015] lr : rfkill_rk_set_power+0xb0/0x394
[    4.695018] sp : ffffffc00d673c30
[    4.695020] x29: ffffffc00d673c30 x28: ffffff8109c77000 x27: 0000000000000000
[    4.695023] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
[    4.695026] x23: 0000000060001000 x22: ffffff8103039080 x21: ffffffc0096c3418
[    4.695029] x20: ffffff8102e2be80 x19: ffffff8102e97118 x18: 0000000000001000
[    4.695032] x17: 0000000000000000 x16: 0000000000000400 x15: 0000000000000000
[    4.695035] x14: 0000000000000400 x13: 3131313131313131 x12: 31313120203a7265
[    4.695038] x11: fffffffffffcf480 x10: ffffffc00a3036b8 x9 : ffffffc009344310
[    4.695041] x8 : ffffffc00a2536b8 x7 : ffffffc00a3036b8 x6 : 0000000000000000
[    4.695043] x5 : ffffff82f6de7ae0 x4 : ffffffc00a3e50b8 x3 : 0000000000000010
[    4.695046] x2 : 0000000000000028 x1 : ffffff8102e964c0 x0 : 0000000000000001
[    4.695049] Call trace:
[    4.695051]  gpiod_get_raw_value+0x58/0xd4
[    4.695053]  rfkill_rk_set_power+0xb0/0x394
[    4.695054]  rfkill_set_block+0xbc/0x234
[    4.695058]  rfkill_fop_write+0x1fc/0x234
[    4.695062]  vfs_write+0xc4/0x374
[    4.695066]  ksys_write+0xdc/0xf4
[    4.695069]  __arm64_sys_write+0x20/0x2c
[    4.695072]  invoke_syscall+0x4c/0x110
[    4.695075]  el0_svc_common.constprop.0+0x54/0x180
[    4.695078]  do_el0_svc+0x20/0x30
[    4.695080]  el0_svc+0x24/0xa4
[    4.695084]  el0t_64_sync_handler+0xb0/0xb4
[    4.695087]  el0t_64_sync+0x174/0x178

原因是驱动中采用gpio_get_value获取GPIO引脚状态时会调用到gpiod_get_raw_value。从代码中可以看到当GPIO的can_sleep是true是就会有警告，但是这个警告不会影响到系统运行。

int gpiod_get_raw_value(const struct gpio_desc *desc)
{VALIDATE_DESC(desc);/* Should be using gpiod_get_raw_value_cansleep() */WARN_ON(desc->gdev->can_sleep);return gpiod_get_raw_value_commit(desc);
}