Messages in this thread | | | Date | Fri, 31 Jul 2009 13:23:13 +0400 | From | Paul Fertser <> | Subject | Re: [PATCH] pcf50633: use a dedicated workqueue for irq processing |
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On Thu, Jul 30, 2009 at 03:34:25PM -0700, Andrew Morton wrote: > On Tue, 28 Jul 2009 00:41:15 +0400 > Paul Fertser <fercerpav@gmail.com> wrote: > > > Using the default kernel "events" workqueue causes problems with > > synchronous adc readings if initiated from some task on the same > > workqueue. > > > > I had a deadlock trying to use pcf50633_adc_sync_read from a > > power_supply class driver because the reading was initiated from the > > workqueue and it waited for the irq processing to complete (to get the > > result) and that was put on the same workqueue. > > I don't get it. > > Do you meant that pcf50633_adc_sync_read() was called via a > schedule_work() handler? If so, wasn't that a bug?
Andrew, i think it is called this way:
power_supply_changed -> schedule_work(&psy->changed_work) -> power_supply_changed_work -> kobject_uevent(&psy->dev->kobj, KOBJ_CHANGE) -> power_supply_uevent -> power_supply_show_property -> get_property -> bat->pdata->get_voltage -> pcf50633_adc_sync_read
I assumed that since power_supply class is well-established and widely used that's an intended behaviour. CCing relevant maintainers to get their opinions.
A bit of background: we sometimes want to use dumb batteries with our openmoko devices (for gta01 aka Neo1973 there's no alternative even), so power_class driver needs to be able to obtain battery voltage measured by PMU.
-- Be free, use free (http://www.gnu.org/philosophy/free-sw.html) software! mailto:fercerpav@gmail.com
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