linux-kernel - Re: Enable arm_global_timer for Zynq brakes boot

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Date:	Mon, 12 Aug 2013 09:32:49 -0700
From:	Sören Brinkmann <soren.brinkmann@...inx.com>
To:	Stephen Boyd <sboyd@...eaurora.org>
CC:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	<srinivas.kandagatla@...com>,
	Russell King <linux@....linux.org.uk>,
	Michal Simek <michal.simek@...inx.com>,
	<linux-kernel@...r.kernel.org>,
	Stuart Menefy <stuart.menefy@...com>,
	John Stultz <john.stultz@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: Enable arm_global_timer for Zynq brakes boot

On Mon, Aug 12, 2013 at 09:20:19AM -0700, Stephen Boyd wrote:
> On 08/12/13 09:03, Sören Brinkmann wrote:
> > On Fri, Aug 09, 2013 at 10:27:57AM -0700, Stephen Boyd wrote:
> >> On 08/09, Daniel Lezcano wrote:
> >>> yes, but at least the broadcast mechanism should send an IPI to cpu0 to
> >>> wake it up, no ? As Stephen stated this kind of configuration should has
> >>> never been tested before so the tick broadcast code is not handling this
> >>> case properly IMHO.
> >>>
> >> If you have a per-cpu tick device that isn't suffering from
> >> FEAT_C3_STOP why wouldn't you use that for the tick versus a
> >> per-cpu tick device that has FEAT_C3_STOP? It sounds like there
> >> is a bug in the preference logic or you should boost the rating
> >> of the arm global timer above the twd. Does this patch help? It
> >> should make the arm global timer the tick device and whatever the
> >> cadence timer you have into the broadcast device.
> > I finally got to test your patch. Unfortunately, it makes the system
> > hang even earlier:
> 
> Sorry it had a bug depending on the registration order. Can you try this
> one (tabs are probably spaces, sorry)? I will go read through this
> thread to see if we already covered the registration order.

That did it! Booted straight into the system. The broadcast device is
the TTC instead of GT, now.

	Tick Device: mode:     1
	Broadcast device
	Clock Event Device: ttc_clockevent
	 max_delta_ns:   1207932479
	 min_delta_ns:   18432
	 mult:           233015
	 shift:          32
	 mode:           1
	 next_event:     9223372036854775807 nsecs
	 set_next_event: ttc_set_next_event
	 set_mode:       ttc_set_mode
	 event_handler:  tick_handle_oneshot_broadcast
	 retries:        0
	
	tick_broadcast_mask: 00000000
	tick_broadcast_oneshot_mask: 00000000
	
	Tick Device: mode:     1
	Per CPU device: 0
	Clock Event Device: arm_global_timer
	 max_delta_ns:   12884902005
	 min_delta_ns:   1000
	 mult:           715827876
	 shift:          31
	 mode:           3
	 next_event:     24216749370 nsecs
	 set_next_event: gt_clockevent_set_next_event
	 set_mode:       gt_clockevent_set_mode
	 event_handler:  hrtimer_interrupt
	 retries:        0
	
	Tick Device: mode:     1
	Per CPU device: 1
	Clock Event Device: arm_global_timer
	 max_delta_ns:   12884902005
	 min_delta_ns:   1000
	 mult:           715827876
	 shift:          31
	 mode:           3
	 next_event:     24220000000 nsecs
	 set_next_event: gt_clockevent_set_next_event
	 set_mode:       gt_clockevent_set_mode
	 event_handler:  hrtimer_interrupt
	 retries:        0


	# cat /proc/interrupts 
	           CPU0       CPU1       
	 27:       1668       1640       GIC  27  gt
	 29:          0          0       GIC  29  twd
	 43:          0          0       GIC  43  ttc_clockevent
	 82:        536          0       GIC  82  xuartps
	IPI0:          0          0  CPU wakeup interrupts
	IPI1:          0          0  Timer broadcast interrupts
	IPI2:       1264       1322  Rescheduling interrupts
	IPI3:          0          0  Function call interrupts
	IPI4:         24         70  Single function call interrupts
	IPI5:          0          0  CPU stop interrupts
	Err:          0


	Thanks,
	Sören


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