On Wed, Mar 28, 2018 at 08:14:05PM +0100, Bryan O'Donoghue wrote:
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] [<c010d630>] (__irq_svc) from [<c0c2e9ec>] (_raw_spin_unlock_irqrestore+0x34/0x44) [ 36.102122] [<c0c2e9ec>] (_raw_spin_unlock_irqrestore) from [<c072e32c>] (regmap_read+0x4c/0x5c) [ 36.110938] [<c072e32c>] (regmap_read) from [<c085d0f4>] (rtc_write_sync_lp+0x6c/0x98) [ 36.118881] [<c085d0f4>] (rtc_write_sync_lp) from [<c085d160>] (snvs_rtc_alarm_irq_enable+0x40/0x4c) [ 36.128041] [<c085d160>] (snvs_rtc_alarm_irq_enable) from [<c08567b4>] (rtc_timer_do_work+0xd8/0x1a8) [ 36.137291] [<c08567b4>] (rtc_timer_do_work) from [<c01441b8>] (process_one_work+0x28c/0x76c) [ 36.145840] [<c01441b8>] (process_one_work) from [<c01446cc>] (worker_thread+0x34/0x58c) [ 36.153961] [<c01446cc>] (worker_thread) from [<c014aee4>] (kthread+0x138/0x150) [ 36.161388] [<c014aee4>] (kthread) from [<c0107e14>] (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] [<c0c288b0>] (__schedule) from [<c0c29134>] (schedule+0x3c/0xa0) [ 36.192739] [<c0c29134>] (schedule) from [<c0c2db80>] (schedule_timeout+0x78/0x4e0) [ 36.200422] [<c0c2db80>] (schedule_timeout) from [<c01a7ab0>] (rcu_gp_kthread+0x648/0x1864) [ 36.208800] [<c01a7ab0>] (rcu_gp_kthread) from [<c014aee4>] (kthread+0x138/0x150) [ 36.216309] [<c014aee4>] (kthread) from [<c0107e14>] (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 pure.logic@nexus-software.ie Cc: a.zummo@towertech.it Cc: alexandre.belloni@free-electrons.com Cc: Pan Bian bianpan2016@163.com Cc: Guy Shapiro guy.shapiro@mobi-wize.com Cc: Stefan Agner stefan@agner.ch Cc: Frank Li Frank.Li@freescale.com Cc: Shawn Guo shawn.guo@linaro.org
Acked-by: Shawn Guo shawn.guo@linaro.org