[PATCH 1/2] firmware: imx: SCU irq should ONLY be enabled after SCU IPC is ready

[Anson Huang]

The imx_scu_irq_group_enable() is normally called during module driver
probe phase to enable SCU group irq, e.g., i.MX system controller
watchdog driver will call it during its driver probe phase, as i.MX
system controller watchdog driver does NOT need SCU IPC handle for
operations, so it could be probed before i.MX SCU IPC is ready, and
below dump will show out:

[    0.933001] Hardware name: Freescale i.MX8QXP MEK (DT)
[    0.938129] pstate: 60000005 (nZCv daif -PAN -UAO)
[    0.942907] pc : imx_scu_call_rpc+0x114/0x158
[    0.947251] lr : imx_scu_irq_group_enable+0x74/0xc4
[    0.952113] sp : ffff00001005bae0
[    0.955415] x29: ffff00001005bae0 x28: ffff0000111bb0a0
[    0.960712] x27: ffff00001140b000 x26: ffff00001111068c
[    0.966011] x25: ffff0000111bb100 x24: 0000000000000000
[    0.971311] x23: ffff0000113d9cd8 x22: 0000000000000001
[    0.976610] x21: 0000000000000001 x20: ffff80083b51a410
[    0.981909] x19: ffff000011259000 x18: 0000000000000480
[    0.987209] x17: 000000000023ffb8 x16: 0000000000000010
[    0.992508] x15: 000000000000023f x14: ffffffffffffffff
[    0.997807] x13: 0000000000000018 x12: 0000000000000030
[    1.003107] x11: 0000000000000003 x10: 0101010101010101
[    1.008406] x9 : ffffffffffffffff x8 : 7f7f7f7f7f7f7f7f
[    1.013706] x7 : fefefeff646c606d x6 : 0000000000000000
[    1.019005] x5 : ffff0000112596c8 x4 : 0000000000000008
[    1.024304] x3 : 0000000000000003 x2 : 0000000000000001
[    1.029604] x1 : ffff00001005bb58 x0 : 0000000000000000
[    1.034905] Call trace:
[    1.037341]  imx_scu_call_rpc+0x114/0x158
[    1.041334]  imx_scu_irq_group_enable+0x74/0xc4
[    1.045856]  imx_sc_wdt_probe+0x24/0x150
[    1.049766]  platform_drv_probe+0x4c/0xb0
[    1.053762]  really_probe+0x1f8/0x2c8
[    1.057407]  driver_probe_device+0x58/0xfc
[    1.061490]  device_driver_attach+0x68/0x70
[    1.065660]  __driver_attach+0x94/0xdc
[    1.069397]  bus_for_each_dev+0x64/0xc0
[    1.073220]  driver_attach+0x20/0x28
[    1.076782]  bus_add_driver+0x148/0x1fc
[    1.080601]  driver_register+0x68/0x120
[    1.084424]  __platform_driver_register+0x4c/0x54
[    1.089120]  imx_sc_wdt_driver_init+0x18/0x20
[    1.093463]  do_one_initcall+0x58/0x1b8
[    1.097287]  kernel_init_freeable+0x1cc/0x288
[    1.101630]  kernel_init+0x10/0x100
[    1.105101]  ret_from_fork+0x10/0x18
[    1.108669] ---[ end trace 9e03302114457de9 ]---
[    1.113296] enable irq failed, group 1, mask 1, ret -22

To avoid such scenario, return -EPROBE_DEFER in imx_scu_irq_group_enable()
API if SCU IPC is NOT ready, then module driver which calls this API
in probe phase will defer probe after SCU IPC ready.

Fixes: 851826c7566e ("firmware: imx: enable imx scu general irq function")
Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
---
 drivers/firmware/imx/imx-scu-irq.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/imx/imx-scu-irq.c b/drivers/firmware/imx/imx-scu-irq.c
index 043833a..687121f 100644
--- a/drivers/firmware/imx/imx-scu-irq.c
+++ b/drivers/firmware/imx/imx-scu-irq.c
@@ -100,6 +100,9 @@ int imx_scu_irq_group_enable(u8 group, u32 mask, u8 enable)
 	struct imx_sc_rpc_msg *hdr = &msg.hdr;
 	int ret;
 
+	if (!imx_sc_irq_ipc_handle)
+		return -EPROBE_DEFER;
+
 	hdr->ver = IMX_SC_RPC_VERSION;
 	hdr->svc = IMX_SC_RPC_SVC_IRQ;
 	hdr->func = IMX_SC_IRQ_FUNC_ENABLE;
-- 
2.7.4