[PATCH] platform/raspberrypi: vchiq: register bus at subsys_initcall

[Martin Wetterwald]

Since the VCHIQ interface was moved out of staging, its bus is no longer
guaranteed to be registered before its client drivers. bcm2835-audio,
still in drivers/staging, registers at device_initcall level and now
runs first:

  Driver 'bcm2835-audio' was unable to register with bus_type
  'vchiq-bus' because the bus was not initialized.

Register the bus and the platform driver at subsys_initcall so the bus
exists before any client driver, independently of link order. The
platform driver probe already returns -EPROBE_DEFER while the firmware
is not ready, so probing earlier is safe. When built as modules, this is
equivalent to module_init() and nothing changes.

Tested on Raspberry Pi 1B rev2, 1B+, 2B, 3B and 4B with VCHIQ and
bcm2835-audio both builtin and both as modules.

Fixes: aa125180c673 ("platform/raspberrypi: Destage VCHIQ interface")
Reported-by: Martin Wetterwald <martin at wetterwald.eu>
Link: https://lore.kernel.org/r/CAFERDQ0FpdVvA5VJxOyRAE_pgxnPVmFx1tkZio5R272j6Bs4tg@mail.gmail.com/
Closes: https://lore.kernel.org/r/CAFERDQ0FpdVvA5VJxOyRAE_pgxnPVmFx1tkZio5R272j6Bs4tg@mail.gmail.com/
Signed-off-by: Martin Wetterwald <martin at wetterwald.eu>
---
 drivers/platform/raspberrypi/vchiq-interface/vchiq_arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/raspberrypi/vchiq-interface/vchiq_arm.c b/drivers/platform/raspberrypi/vchiq-interface/vchiq_arm.c
index e78641703252..d35f5ac5c2e2 100644
--- a/drivers/platform/raspberrypi/vchiq-interface/vchiq_arm.c
+++ b/drivers/platform/raspberrypi/vchiq-interface/vchiq_arm.c
@@ -1462,7 +1462,7 @@ static int __init vchiq_driver_init(void)
 
 	return ret;
 }
-module_init(vchiq_driver_init);
+subsys_initcall(vchiq_driver_init);
 
 static void __exit vchiq_driver_exit(void)
 {
-- 
2.55.0