On 11/13/2015 02:48 PM, Grygorii Strashko wrote: > On 11/12/2015 08:06 PM, Felipe Balbi wrote: >> Make sure to tell the kernel that AM437x has >> TWD and global timers. >> >> Signed-off-by: Felipe Balbi <balbi@xxxxxx> >> --- >> >> Hi Tony, >> >> now that all dependencies are in place, we can >> finally enable twd and global_timer for AM437x. >> > > I'd appreciated if someone can clarify if all described below is valid. > (may be some questions are dummy - sorry). > > After all last changes related to TI OMAP clock source/clock event/sched clock's > devices configuration we will have the following for am437x case: > > clockevents: > "timer1", clockevent_gpt, .rating = 300, CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, ti,timer-alwon, > "arm,twd-timer", twd_evt,.rating = 350, CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP > "arm_global_timer", gt_evt, rating = 300, CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERCPU > > clocksources: > "jiffies", clocksource_jiffies, rating = 1 > if use_gptimer_clksrc > "timer2", clocksource_gpt, .rating = 300, CLOCK_SOURCE_IS_CONTINUOUS, > |-sched_clock_register(dmtimer_read_sched_clock, 32, clksrc.rate); > else > "ti,omap-counter32k", ti_32k_timer, .rating = 250, CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP, > |-sched_clock_register(omap_32k_read_sched_clock, 32, 32768); > > "arm,global-timer", gt_clocksource, .rating = 300, CLOCK_SOURCE_IS_CONTINUOUS > |-sched_clock_register(gt_sched_clock_read, 64, gt_clk_rate); > > 1) current clockevent device will be registered during registration of clockevent devices > and it will be "arm,twd-timer" - processing sequence follows the way they are listed above. > > 2) current clocksource will be selected from fs_initcall(clocksource_done_booting); > and it will be "arm,global-timer" or "timer2" if use_gptimer_clksrc > > 3) sched clock: "arm,global-timer" will be selected as sched_clock *always*, > because it depend on Makefile order (if someone will decide to sort entries > in drivers/clocksource/Makefile then "ti,omap-counter32k" most probably will > be always selected as sched clock). Ok. Sry. Above is not completely true. There are no dependency on makefile and sched clock with Max freq will be selected - and never changed even if corresponding clocksource can be changed through sysfs. > > Uh.. > > As for me, "timer1" is selected as clockevent device incorrectly, because it's > ti,timer-alwon. > > I think, "ti,omap-counter32k" will crash if use_gptimer_clksrc == true, because > corresponding HWmod will not be enabled (not tested this case). Ok. Below is confirmation for the case if use_gptimer_clksrc == true, so https://www.spinics.net/lists/linux-omap/msg122576.html "[PATCH 00/11] arm: omap: counter32k rework" introduces regression !? cat /sys/devices/system/clocksource/clocksource0/available_clocksource timer2 arm_global_timer 32k_counter / # echo 32k_counter > /sys/devices/system/clocksource/clocksource0/current_cloc ksource [ 102.194313] Unhandled fault: imprecise external abort (0x1406) at 0x0020ab5c [ 102.197862] pgd = ee22c000 -- regards, -grygorii -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
