Fix potential merge conflict for dw_apb_timer_of

Am Dienstag, 18. Juni 2013, 17:38:35 schrieb Heiko St?bner:

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Hi Pavel,

Am Dienstag, 18. Juni 2013, 17:02:44 schrieb Pavel Machek:

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Hi!

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The following 2 patches will eliminate the need for the patch in John Stultz's tree. If there is to be merge of the 2 trees, then the patch:

dw_apb_timer_of.c: Remove parts that were picoxcell-specific

can be removed from John's tree to avoid a merge-conflict.

Based on arm-soc/for-next:

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PATCH[1/2] - Rename "dw-apb-timer-osc" and "dw-apb-timer-sp" bindings to just "dw-apb-timer"
PATCH[2/2] - Fix user/system reporting by fixing read_sched_clock()

Pavel/Jamie: Can you take a look at these too and make sure these cover what you were doing.

[It seems like Heiko St?bner was not aware of patches in the clock tree, so did pretty much equivalent patch.]

Correct ... I was going after what was in linux-next and the tip.git [which I also only saw recently at all] does not seem to be part of it.

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Dinh's changes look good to me, but

[PATCH v2 4/4] clocksource: dw_apb_timer_of: use clocksource_of_init

does not exactly look nice: (I'm sorry I did not see original series, before it was merged to -soc.). The function counts number of times it was called, and behaves differently in each case. It is not very traditional kernel code at the very least.

(quoted diff) +2 -8

+static int num_called;
+static void __init dw_apb_timer_init(struct device_node *timer)
 
  {
 
-       struct device_node *event_timer, *source_timer;
-
-       event_timer = of_find_matching_node(NULL, osctimer_ids);
-       if (!event_timer)
-               panic("No timer for clockevent");
-       add_clockevent(event_timer);
-
-       source_timer = of_find_matching_node(event_timer,

osctimer_ids);

(quoted diff) +15 -5

-       if (!source_timer)
-               panic("No timer for clocksource");
-       add_clocksource(source_timer);
-
-       of_node_put(source_timer);
+       switch (num_called) {
+       case 0:
+               pr_debug("%s: found clockevent timer\n", __func__);
+               add_clockevent(timer);
+               of_node_put(timer);
+               break;
+       case 1:
+               pr_debug("%s: found clocksource timer\n", __func__);
+               add_clocksource(timer);
+               of_node_put(timer);
+               init_sched_clock();
+               break;
+       default:
+               break;
+       }

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(quoted diff) +1 -1

-       init_sched_clock();
+       num_called++;
 
  }

Heiko, can you take a look at John Stultz tree? We modified this area already... I understand you only have one timer on your silicon?

also it seems like not being able to use the apb_timer as sched_clock will hurt my platform too.

I've tried to use the arm_arch_timer, but when the arch_timer_get_cntfrq() function gets called, I only get an "undefined instruction" Oops for the executed asm in there.

As there is no manual available for the SoC, I can only guess that it doesn't contain such a component. This is fueled additionally by the PPI part of the gic only having 3 interrupt sources [there is small excerpt of the soc-manual floating around that contains this information], with one already being the twd interrupt, while the arm_arch_timer seems to require 4 itself.

Therefore it would cool, if we could keep the sched_clock functionality (provided by the clocksource timer) around somehow.