On Fri, Mar 15, 2013 at 2:53 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: > What exactly is the spinlock protecting against here? Concurrent runs of > exynos_adc_isr? This is probably not issue in the first place. > > What you want to protect against is that completion is completed between the > call to INIT_COMPLETION() and the start of a new conversion. So the sections > that need to be under the spinlock are the complete call here and the point > from INIT_COMPLETION until the transfer is started in exynos_read_raw(). Make > sure to use spin_lock_irq there. ...and at that point I _think_ you won't also need the mutex. A reasonable way to test to see if you've got this all correct would be to: * Start two processes that are reading from different ADCs that will report very different values (maybe add a device tree node for adc1 or adc7 and use those since they're not really connected to thermistors?). * Have your two processes read as fast as they can. This could just be "while true; do cat /sys/class/hwmon/hwmon0/device/temp1_input; done" * Decrease your timeout and maybe(?) sprinkle some random udelays in the irq handler so that the timeouts happen sometimes but not others. * Periodically cancel one of the readers with Ctrl-C If all is working well then you should always get back the right value from the right reader (and get no crashes). -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
