From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH V2 2/6] ARM: tegra20: cpuidle: add powered-down state for secondary CPU
Date: Wed, 05 Dec 2012 15:18:14 -0700 [thread overview]
Message-ID: <50BFC826.1020705@wwwdotorg.org> (raw)
In-Reply-To: <1354701715-24150-3-git-send-email-josephl@nvidia.com>
On 12/05/2012 03:01 AM, Joseph Lo wrote:
> The powered-down state of Tegra20 requires power gating both CPU cores.
> When the secondary CPU requests to enter powered-down state, it saves
> its own contexts and then enters WFI. The Tegra20 had a limition to
> power down both CPU cores. The secondary CPU must waits for CPU0 in
> powered-down state too. If the secondary CPU be woken up before CPU0
> entering powered-down state, then it needs to restore its CPU states
> and waits for next chance.
>
> Be aware of that, you may see the legacy power state "LP2" in the code
> which is exactly the same meaning of "CPU power down".
> diff --git a/arch/arm/mach-tegra/cpuidle-tegra20.c b/arch/arm/mach-tegra/cpuidle-tegra20.c
> +static int __cpuinit tegra20_idle_lp2(struct cpuidle_device *dev,
> + return (entered_lp2) ? index : 0;
No need for the brackets there.
BTW, could you Cc Colin Cross on any future revisions of these patches;
it'd be good to get his take on them.
> diff --git a/arch/arm/mach-tegra/sleep-tegra20.S b/arch/arm/mach-tegra/sleep-tegra20.S
> +/*
> + * tegra_pen_lock
> + * on cpu 0:
> + * SCRATCH38 = r2 = flag[0]
> + * SCRATCH39 = r3 = flag[1]
It would be slightly clearer if that was written:
* r2 = flag[0] (in SCRATCH38)
* r3 = flag[1] (in SCRATCH39)
since the meaning of r2/r3 is what's being selected.
> + mov r12, #1
> + str r12, [r2] @ flag[cpu] = 1
> + dsb
> + str r12, [r1] @ !turn = cpu
Should that be "str r0, [r1]"? Otherwise, you're always writing 1 there,
not writing the CPU ID as expected.
next prev parent reply other threads:[~2012-12-05 22:18 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-05 10:01 [PATCH V2 0/6] ARM: tegra20: cpuidle: add power-down state Joseph Lo
2012-12-05 10:01 ` [PATCH V2 1/6] ARM: tegra: add pending SGI checking API Joseph Lo
2012-12-05 22:09 ` Stephen Warren
2012-12-06 7:04 ` Joseph Lo
2012-12-06 18:52 ` Stephen Warren
2012-12-05 10:01 ` [PATCH V2 2/6] ARM: tegra20: cpuidle: add powered-down state for secondary CPU Joseph Lo
2012-12-05 10:50 ` Lorenzo Pieralisi
2012-12-06 8:25 ` Joseph Lo
2012-12-06 18:56 ` Stephen Warren
2013-01-11 7:20 ` Joseph Lo
2013-01-11 12:24 ` Lorenzo Pieralisi
2013-01-15 3:00 ` Joseph Lo
2013-01-15 11:34 ` Lorenzo Pieralisi
2013-01-16 3:17 ` Joseph Lo
2013-01-12 17:33 ` Nicolas Pitre
2012-12-05 22:18 ` Stephen Warren [this message]
2012-12-06 7:22 ` Joseph Lo
2012-12-06 18:59 ` Stephen Warren
2012-12-05 10:01 ` [PATCH V2 3/6] ARM: tegra20: clocks: add CPU low-power function into tegra_cpu_car_ops Joseph Lo
2012-12-05 10:01 ` [PATCH V2 4/6] ARM: tegra20: flowctrl: add support for cpu_suspend_enter/exit Joseph Lo
2012-12-05 10:01 ` [PATCH V2 5/6] ARM: tegra20: cpuidle: add powered-down state for CPU0 Joseph Lo
2012-12-05 10:01 ` [PATCH V2 6/6] ARM: tegra20: cpuidle: apply coupled cpuidle for powered-down mode Joseph Lo
2012-12-05 10:01 ` Joseph Lo
2012-12-05 10:10 ` Joseph Lo
2012-12-06 11:03 ` Grant Likely
2012-12-05 10:01 ` Joseph Lo
2012-12-05 10:11 ` Joseph Lo
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=50BFC826.1020705@wwwdotorg.org \
--to=swarren@wwwdotorg$(echo .)org \
--cc=linux-arm-kernel@lists$(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