On 14/06/18 04:20, Chanwoo Choi wrote: > Hi Roger, > > On 2018년 06월 11일 17:53, Roger Quadros wrote: >> Chanwoo, >> >> On 11/06/18 11:33, H. Nikolaus Schaller wrote: >>> Hi Tony, >>> another bug... >>> >>> [ 174.540313] BUG: scheduling while atomic: kworker/0:4/1327/0x00000002 >>> [ 174.547353] Modules linked in: omapdrm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm drm_panel_orientation_quirks bnep bluetooth ecdh_generic usb_f_ecm g_ether usb_f_rndis u_ether libcomposite configfs ipv6 arc4 wl18xx wlcore mac80211 panel_boe_w677l snd_soc_omap_hdmi_audio snd_soc_dmic cfg80211 dwc3 snd_soc_omap_abe_twl6040 snd_soc_twl6040 leds_gpio wwan_on_off connector_hdmi omapdss encoder_tpd12s015 cec pwm_omap_dmtimer omapdss_base pwm_bl generic_adc_battery ehci_omap wlcore_sdio dwc3_omap bmp280_spi snd_soc_ts3a227e crtouch_mt leds_is31fl319x tsc2007 bq2429x_charger bq27xxx_battery_i2c bq27xxx_battery ina2xx as5013 tca8418_keypad twl6040_vibra palmas_pwrbutton gpio_twl6040 palmas_gpadc usb3503 bmp280_i2c bmc150_accel_i2c w2cbw003_bluetooth bmc150_magn_i2c bmp280 bmc150_accel_core >>> [ 174.624601] bmc150_magn bno055 industrialio_triggered_buffer kfifo_buf industrialio snd_soc_omap_mcbsp snd_soc_omap_mcpdm snd_soc_omap snd_pcm_dmaengine [last unloaded: syscopyarea] >>> [ 174.642327] CPU: 0 PID: 1327 Comm: kworker/0:4 Tainted: G W 4.17.0-letux+ #2408 >>> [ 174.651541] Hardware name: Generic OMAP5 (Flattened Device Tree) >>> [ 174.658004] Workqueue: events_power_efficient palmas_gpio_id_detect >>> [ 174.664780] [<c01106ec>] (unwind_backtrace) from [<c010c058>] (show_stack+0x10/0x14) >>> [ 174.673109] [<c010c058>] (show_stack) from [<c074ba68>] (dump_stack+0x7c/0x9c) >>> [ 174.680881] [<c074ba68>] (dump_stack) from [<c0154050>] (__schedule_bug+0x60/0x84) >>> [ 174.689006] [<c0154050>] (__schedule_bug) from [<c075e3c0>] (__schedule+0x50/0x694) >>> [ 174.697217] [<c075e3c0>] (__schedule) from [<c075eab4>] (schedule+0xb0/0xcc) >>> [ 174.704790] [<c075eab4>] (schedule) from [<c0761e58>] (schedule_timeout+0x354/0x3d4) >>> [ 174.713100] [<c0761e58>] (schedule_timeout) from [<c075f544>] (wait_for_common+0x118/0x158) >>> [ 174.722064] [<c075f544>] (wait_for_common) from [<c05de908>] (omap_i2c_xfer+0x354/0x48c) >>> [ 174.730749] [<c05de908>] (omap_i2c_xfer) from [<c05d8410>] (__i2c_transfer+0x238/0x550) >>> [ 174.739350] [<c05d8410>] (__i2c_transfer) from [<c05d87ac>] (i2c_transfer+0x84/0xb4) >>> [ 174.747685] [<c05d87ac>] (i2c_transfer) from [<bf15b1f0>] (bq24296_i2c_reg8_read.constprop.8+0x54/0x64 [bq2429x_charger]) >>> [ 174.759465] [<bf15b1f0>] (bq24296_i2c_reg8_read.constprop.8 [bq2429x_charger]) from [<bf15b8f4>] (bq24296_update_reg+0x28/0xf8 [bq2429x_charger]) >>> [ 174.773437] [<bf15b8f4>] (bq24296_update_reg [bq2429x_charger]) from [<c0493b2c>] (_regulator_do_disable+0x100/0x238) >>> [ 174.784804] [<c0493b2c>] (_regulator_do_disable) from [<c0493cec>] (_regulator_disable+0x88/0x120) >>> [ 174.794404] [<c0493cec>] (_regulator_disable) from [<c0493db4>] (regulator_disable+0x30/0x60) >>> [ 174.803556] [<c0493db4>] (regulator_disable) from [<bf1950c8>] (dwc3_omap_set_mailbox+0x84/0xf8 [dwc3_omap]) >>> [ 174.814124] [<bf1950c8>] (dwc3_omap_set_mailbox [dwc3_omap]) from [<bf195198>] (dwc3_omap_id_notifier+0x14/0x1c [dwc3_omap]) >>> [ 174.826149] [<bf195198>] (dwc3_omap_id_notifier [dwc3_omap]) from [<c014e458>] (notifier_call_chain+0x40/0x68) >>> [ 174.836867] [<c014e458>] (notifier_call_chain) from [<c014e4a0>] (raw_notifier_call_chain+0x14/0x1c) >>> [ 174.846661] [<c014e4a0>] (raw_notifier_call_chain) from [<c063bda4>] (extcon_sync+0x54/0x19c) >>> [ 174.855804] [<c063bda4>] (extcon_sync) from [<c014874c>] (process_one_work+0x244/0x464) >>> [ 174.864386] [<c014874c>] (process_one_work) from [<c0148f20>] (worker_thread+0x2c0/0x3ec) >>> [ 174.873156] [<c0148f20>] (worker_thread) from [<c014cef4>] (kthread+0x134/0x150) >>> [ 174.881087] [<c014cef4>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c) >>> >>> It turns out that extcon_sync() holds a spinlock while sending its notifiers and this >>> is ending up in our regulator.en/disable() which wants to use blocking i2c. >>> >>> Do you see similar things on the OMAP5EVM when using OTG mode? >>> The Palmas SMPS10 is also handled through i2c. Or is this magically hidden by regmap? >>> >>> Well, as a workaround, I can make the regulator.en/disable() in the bq2429x driver >>> just trigger a worker, but IMHO it is not expected for regulator ops to be spinlock safe. >>> >>> So I think extcon should not spinlock (which might be against the extcon design) or >> >> I think this something that should be addressed in the Extcon layer. >> Do you really need to call the raw_notifier_call_chain() function with spinlock held in extcon_sync()? >> if yes why? > > To reduce the latency of notification is important of extcon. > > So, extcon used the spinlock before calling the notifier_call_chain > to prevent the scheduled out for a moment. Also, the notifier_call > calls the registered notifier function sequentially. It means that > if some registered notifier function spends a lot of time, > the next registered notifier might receive the notification > with a delay. So, extcon used the spinlock. Unitl now, > > But, as you commented and previously, sometimes it caused the similar issues. > (To fix similar issues, the consumer device used the workqueue) > > I will call notifier function without spinlock as following > and I'll consider the other way to notify the changed state to consumer device > with broadcasting way. > > diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c > index 8bff5fd18185..1e35b8ca3951 100644 > --- a/drivers/extcon/extcon.c > +++ b/drivers/extcon/extcon.c > @@ -433,8 +433,8 @@ int extcon_sync(struct extcon_dev *edev, unsigned int id) > return index; > > spin_lock_irqsave(&edev->lock, flags); > - > state = !!(edev->state & BIT(index)); > + spin_unlock_irqrestore(&edev->lock, flags); > > /* > * Call functions in a raw notifier chain for the specific one > @@ -448,6 +448,8 @@ int extcon_sync(struct extcon_dev *edev, unsigned int id) > */ > raw_notifier_call_chain(&edev->nh_all, state, edev); > > + spin_lock_irqsave(&edev->lock, flags); > + > Thanks Chanwoo. Nikolaus, could you please test this patch and give your Reported-by/Tested-by sign off? Thanks. https://lkml.org/lkml/2018/6/14/2 >> >> I think we don't want to call all notifiers in atomic context as this would keep interrupts disabled >> for quite some time and is suboptimal. >> >>> dwc3_omap_set_mailbox should move dis/enabling regulator to some worker thread so >>> that they can block. >>> >>> The best would be to make dwc3_omap_set_mailbox call regulator_enable_deferred(omap->vbus_reg, 0) >>> but that function does not exist. >>> >>> Any ideas? >>> >>> BR, >>> Nikolaus >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-omap" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> > > -- cheers, -roger Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
