From: grygorii.strashko@ti•com (Grygorii Strashko)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] arm: omap2: Kconfig: select TWD and global timer on AM43xx devices
Date: Wed, 18 Nov 2015 16:33:37 +0200 [thread overview]
Message-ID: <564C8C41.9080006@ti.com> (raw)
In-Reply-To: <56461256.5050209@oracle.com>
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@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
clocksource device.
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:
http://www.spinics.net/lists/arm-kernel/msg461141.html
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
Thanks.
--
regards,
-grygorii
next prev parent reply other threads:[~2015-11-18 14:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-12 18:06 [PATCH] arm: omap2: Kconfig: select TWD and global timer on AM43xx devices Felipe Balbi
2015-11-13 12:48 ` Grygorii Strashko
2015-11-13 13:07 ` Mason
2015-11-13 16:39 ` santosh shilimkar
2015-11-18 14:33 ` Grygorii Strashko [this message]
2015-11-18 18:01 ` santosh shilimkar
2015-11-13 17:15 ` Grygorii Strashko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=564C8C41.9080006@ti.com \
--to=grygorii.strashko@ti$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox