On Fri, May 15, 2015 at 11:29:34AM +0200, Mason wrote: > On 14/05/2015 16:42, Russell King - ARM Linux wrote: > > > If it's in periodic mode, the update should still be propagated to the > > hardware, assuming the generic time keeping code doesn't produce an > > error. > > > > twd_update_frequency > > `-clockevents_update_freq > > `-__clockevents_update_freq > > `-__clockevents_set_state(, CLOCK_EVT_STATE_PERIODIC) > > `-dev->set_mode (twd_set_mode) > > > > That re-writes the TWD_TIMER_LOAD register based on twd_timer_rate, > > which would have been updated by twd_update_frequency(). > > > > The question I posed earlier remains: is clockevents_update_freq() > > failing? We don't know, because we never check its return value. > > > > Another thing to look at is whether we reach twd_set_mode(). > > > > Lastly, printing the values of the TWD_TIMER_LOAD and TWD_TIMER_COUNTER > > after twd_set_mode() has written TWD_TIMER_LOAD might provide some > > hints as to what's going on. > > I'll have access to the board on Monday. > > I'll add printk in strategic places, and report back ASAP. That would be good. > (I'm considering dropping TWD, and using platform timers.) As you don't say which kernel version you're using, for all we know, you might be using a version which omits some fixes in this area, such as this one which you really must have if your timer is operating in period mode: fe79a9ba1196 clockevents: Adjust timer interval when frequency changes -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
