[PATCH] arm: omap2: Kconfig: select TWD and global timer on AM43xx devices
grygorii.strashko at ti.com
Wed Nov 18 06:33:37 PST 2015
On 11/13/2015 06:39 PM, santosh shilimkar wrote:
> On 11/13/2015 5:07 AM, Mason wrote:
>> On 13/11/2015 13:48, 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 at ti.com>
>>>> Hi Tony,
>>>> now that all dependencies are in place, we can
>>>> finally enable twd and global_timer for AM437x.
> Is AM437x SMP SOC ?
No. But it has ARM TWD and GT
> Is TWD on AM437x works in low power states ?
No. But TWD, seems, is not a problem here if omap gp timer
can be used as broadcast device.
> Probably I haven't followed the recent updates, but does
> the TWD supports C3STOP on UP systems ? The broadcast
> code was SMP only in past, and TWD use to die in
> low power state on past OMAP SOCs.
> If either of these are still the issue then
> TWD shouldn't be used.
Yep. I see the problem with ARM Global timer here if
CPUIdle is enabled and ARM Global timer is selected as
I think, it will be right thing to disable "global_timer"
and "local_timer" nodes in am437x.dtsi by default - if
someone would like to use them then those nodes have
to be enabled explicitly in board file.
(TWD timer will be enabled on OMAP multi SoC build
irrespectively of HAVE_ARM_TWD is selected for am437x or not,
because it will be selected for omap4).
I've just sent corresponding patch:
Also, probably, it could be reasonable to:
- make ARM_GLOBAL_TIMER fully selectable option and allow select it from defconfig.
- or - update this patch as below
- select ARM_GLOBAL_TIMER
- select CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
+ select ARM_GLOBAL_TIMER if !CPU_IDLE
+ select CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK if ARM_GLOBAL_TIMER
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