[PATCH] clocksource/drivers/timer-mediatek: error out on probe defer

[Matthias Brugger]

If the clocks are not yet present, because they are loaded after
the timer is initialized, we are unable to boot.
Check if the return value of timer_of_init and return on EPROBE_DEFER.

Error seen is:
[    0.008337] Failed to get clock for /timer@10004000
[    0.013435] WARNING: CPU: 0 PID: 0 at ../drivers/clk/clk.c:3615
__clk_put+0xf0/0x120
[    0.021453] Modules linked in:
[    0.024614] CPU: 0 PID: 0 Comm: swapper/0 Not tainted
4.20.0-rc1-00063-g2859d9abd7e8 #2
[    0.032902] Hardware name: MediaTek MT7622 RFB1 board (DT)
[    0.038580] pstate: 20000085 (nzCv daIf -PAN -UAO)
[    0.043538] pc : __clk_put+0xf0/0x120
[    0.047328] lr : clk_put+0xc/0x18
[    0.050753] sp : ffff000009163ed0
[    0.054178] x29: ffff000009163ed0 x28: 0000000041010018
[    0.059676] x27: 0000000000000000 x26: 0000000000000000
[    0.065174] x25: ffff0000090cb008 x24: ffff80001dfd7800
[    0.070672] x23: ffff000008f934b8 x22: ffff80001dfdeae0
[    0.076169] x21: ffff80001dfdeae0 x20: fffffffffffffdfb
[    0.081668] x19: ffff00000929ac40 x18: ffffffffffffffff
[    0.087166] x17: 0000000000000000 x16: 0000000000000000
[    0.092664] x15: ffff0000091696c8 x14: ffff0000892cd70f
[    0.098162] x13: ffff0000092cd71d x12: ffff000009181348
[    0.103661] x11: ffff000009181000 x10: 0000000005f5e0ff
[    0.109159] x9 : 0000000000000040 x8 : ffff000009181400
[    0.114657] x7 : ffff80001c800270 x6 : 0000000000000000
[    0.120155] x5 : ffff80001c800248 x4 : 0000000000000000
[    0.125653] x3 : 0000000000000000 x2 : 0000000000000000
[    0.131151] x1 : 0000000000000000 x0 : fffffffffffffdfb
[    0.136649] Call trace:
[    0.139175]  __clk_put+0xf0/0x120
[    0.142605]  timer_of_cleanup+0x60/0x7c
[    0.146572]  mtk_gpt_init+0x18c/0x1a0
[    0.150359]  timer_probe+0x74/0x10c
[    0.153969]  time_init+0x14/0x44
[    0.157307]  start_kernel+0x29c/0x414
[    0.161098] ---[ end trace c3137b005300b618 ]---

Fixes: a0858f937960 ("clocksource/drivers/timer-mediatek: Convert the driver to
timer-of")
Fixes: e3af677607d9 ("clocksource/drivers/timer-mediatek: Add support for system
timer")
Signed-off-by: Matthias Brugger <matthias.bgg@xxxxxxxxx>
---
 drivers/clocksource/timer-mediatek.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/clocksource/timer-mediatek.c
b/drivers/clocksource/timer-mediatek.c
index eb10321f8517..d40c77a65b08 100644
--- a/drivers/clocksource/timer-mediatek.c
+++ b/drivers/clocksource/timer-mediatek.c
@@ -276,8 +276,12 @@ static int __init mtk_syst_init(struct device_node *node)
 	to.of_irq.handler = mtk_syst_handler;

 	ret = timer_of_init(node, &to);
-	if (ret)
+	if (ret) {
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
 		goto err;
+	}

 	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
 					TIMER_SYNC_TICKS, 0xffffffff);
@@ -301,8 +305,12 @@ static int __init mtk_gpt_init(struct device_node *node)
 	to.of_irq.handler = mtk_gpt_interrupt;

 	ret = timer_of_init(node, &to);
-	if (ret)
+	if (ret) {
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
 		goto err;
+	}

 	/* Configure clock source */
 	mtk_gpt_setup(&to, TIMER_CLK_SRC, GPT_CTRL_OP_FREERUN);
-- 
2.19.1