From 1485991c024603b2fb4ae77beb7a0d741128a48e Mon Sep 17 00:00:00 2001 From: Bryan O'Donoghue Date: Wed, 28 Mar 2018 20:14:05 +0100 Subject: [PATCH] rtc: snvs: Fix usage of snvs_rtc_enable commit 179a502f8c46 ("rtc: snvs: add Freescale rtc-snvs driver") introduces the SNVS RTC driver with a function snvs_rtc_enable(). snvs_rtc_enable() can return an error on the enable path however this driver does not currently trap that failure on the probe() path and consequently if enabling the RTC fails we encounter a later error spinning forever in rtc_write_sync_lp(). [ 36.093481] [] (__irq_svc) from [] (_raw_spin_unlock_irqrestore+0x34/0x44) [ 36.102122] [] (_raw_spin_unlock_irqrestore) from [] (regmap_read+0x4c/0x5c) [ 36.110938] [] (regmap_read) from [] (rtc_write_sync_lp+0x6c/0x98) [ 36.118881] [] (rtc_write_sync_lp) from [] (snvs_rtc_alarm_irq_enable+0x40/0x4c) [ 36.128041] [] (snvs_rtc_alarm_irq_enable) from [] (rtc_timer_do_work+0xd8/0x1a8) [ 36.137291] [] (rtc_timer_do_work) from [] (process_one_work+0x28c/0x76c) [ 36.145840] [] (process_one_work) from [] (worker_thread+0x34/0x58c) [ 36.153961] [] (worker_thread) from [] (kthread+0x138/0x150) [ 36.161388] [] (kthread) from [] (ret_from_fork+0x14/0x20) [ 36.168635] rcu_sched kthread starved for 2602 jiffies! g496 c495 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0 [ 36.178564] rcu_sched R running task 0 8 2 0x00000000 [ 36.185664] [] (__schedule) from [] (schedule+0x3c/0xa0) [ 36.192739] [] (schedule) from [] (schedule_timeout+0x78/0x4e0) [ 36.200422] [] (schedule_timeout) from [] (rcu_gp_kthread+0x648/0x1864) [ 36.208800] [] (rcu_gp_kthread) from [] (kthread+0x138/0x150) [ 36.216309] [] (kthread) from [] (ret_from_fork+0x14/0x20) This patch fixes by parsing the result of rtc_write_sync_lp() and propagating both in the probe and elsewhere. If the RTC doesn't start we don't proceed loading the driver and don't get into this loop mess later on. Fixes: 179a502f8c46 ("rtc: snvs: add Freescale rtc-snvs driver") Signed-off-by: Bryan O'Donoghue Acked-by: Shawn Guo Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-snvs.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c index d8ef9e0..9af591d 100644 --- a/drivers/rtc/rtc-snvs.c +++ b/drivers/rtc/rtc-snvs.c @@ -132,20 +132,23 @@ static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm) { struct snvs_rtc_data *data = dev_get_drvdata(dev); unsigned long time; + int ret; rtc_tm_to_time(tm, &time); /* Disable RTC first */ - snvs_rtc_enable(data, false); + ret = snvs_rtc_enable(data, false); + if (ret) + return ret; /* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */ regmap_write(data->regmap, data->offset + SNVS_LPSRTCLR, time << CNTR_TO_SECS_SH); regmap_write(data->regmap, data->offset + SNVS_LPSRTCMR, time >> (32 - CNTR_TO_SECS_SH)); /* Enable RTC again */ - snvs_rtc_enable(data, true); + ret = snvs_rtc_enable(data, true); - return 0; + return ret; } static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) @@ -288,7 +291,11 @@ static int snvs_rtc_probe(struct platform_device *pdev) regmap_write(data->regmap, data->offset + SNVS_LPSR, 0xffffffff); /* Enable RTC */ - snvs_rtc_enable(data, true); + ret = snvs_rtc_enable(data, true); + if (ret) { + dev_err(&pdev->dev, "failed to enable rtc %d\n", ret); + goto error_rtc_device_register; + } device_init_wakeup(&pdev->dev, true); -- 2.7.4