From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 6/6] ARM: tegra114: add CPU hotplug support
Date: Thu, 16 May 2013 12:26:49 -0600 [thread overview]
Message-ID: <519524E9.8000401@wwwdotorg.org> (raw)
In-Reply-To: <1368702862.7403.86.camel@jlo-ubuntu-64.nvidia.com>
On 05/16/2013 05:14 AM, Joseph Lo wrote:
> On Thu, 2013-05-16 at 07:11 +0800, Stephen Warren wrote:
>> On 05/15/2013 04:27 AM, Joseph Lo wrote:
>>> The Tegra114 is a quad cores SoC. Each core can be hotplugged including
>>> CPU0. The hotplug sequence can be controlled by setting event trigger in
>>> flow controller. Then the flow controller will take care all the power
>>> sequence that include CPU up and down.
>>> tst r0, #TEGRA30_POWER_HOTPLUG_SHUTDOWN
>>> + beq flow_ctrl_setting_for_lp2
>>> +
>>> + /* flow controller set up for hotplug */
>>> + mov r3, #FLOW_CTRL_WAITEVENT @ For hotplug
>>> + b flow_ctrl_done
>>> +flow_ctrl_setting_for_lp2:
>>> + /* flow controller set up for LP2 */
>>> + cmp r10, #(TEGRA30 << 8)
>>> moveq r3, #FLOW_CTRL_WAIT_FOR_INTERRUPT @ For LP2
>>
>> Do you need e.g. "movne r3, #0" or similar here? Otherwise, I think r3
>> ends up not being initialized.
>
> Yes, I will add the code when I add LP2 support for Tegra114 later.
> Currently the LP2 code flow only for Tegra30, so it's OK.
Ah, I see. Can we add the extra move to make sure the register is always
initialized now even though the path won't be used. That way, nobody
will be confused by this.
>>> - movne r3, #FLOW_CTRL_WAITEVENT @ For hotplug
>>> +flow_ctrl_done:
>>> + cmp r10, #(TEGRA30 << 8)
>>> str r3, [r2]
>>
>> I wonder whether creating a separate tegra114_cpu_shutdown() wouldn't be
>> better, to avoid all the runtime conditional code.
>
> I personally think the conditional code is OK. And the ARM CPU also had
> hardware for branch detection also.
>
> I had finished some further features for both Tegra30 and Tegra114. And
> most of the code here can be shared each other at least until now I
> could see. Once I see if there is a significant difference, then I would
> prepare maintain the code separately too.
OK, if the function gets larger with more shared, I guess it's fine.
Right now, the conditional-to-non-conditional code ratio is pretty high.
next prev parent reply other threads:[~2013-05-16 18:26 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-15 10:27 [PATCH 0/6] ARM: tegra114: add CPU hotplug support Joseph Lo
2013-05-15 10:27 ` [PATCH 1/6] ARM: tegra: add an assembly marco to check Tegra SoC ID Joseph Lo
2013-05-15 22:43 ` Stephen Warren
2013-05-16 10:09 ` Joseph Lo
2013-05-16 18:21 ` Stephen Warren
2013-05-15 10:27 ` [PATCH 2/6] ARM: tegra: skip SCU and PL310 code when CPU is not Cortex-A9 Joseph Lo
2013-05-15 22:48 ` Stephen Warren
2013-05-16 10:13 ` Joseph Lo
2013-05-15 10:27 ` [PATCH 3/6] ARM: tegra: make tegra_resume can work for Tegra114 Joseph Lo
2013-05-15 22:57 ` Stephen Warren
2013-05-16 10:35 ` Joseph Lo
2013-05-16 18:24 ` Stephen Warren
2013-05-15 10:27 ` [PATCH 4/6] ARM: tegra114: add power up sequence for warm boot CPU Joseph Lo
2013-05-15 10:27 ` [PATCH 5/6] clk: tegra114: implement wait_for_reset and disable_clock for tegra_cpu_car_ops Joseph Lo
2013-05-15 23:02 ` Stephen Warren
2013-05-16 19:17 ` Mike Turquette
2013-05-15 10:27 ` [PATCH 6/6] ARM: tegra114: add CPU hotplug support Joseph Lo
2013-05-15 23:11 ` Stephen Warren
2013-05-16 11:14 ` Joseph Lo
2013-05-16 18:26 ` Stephen Warren [this message]
2013-05-15 23:38 ` [PATCH 0/6] " Stephen Warren
2013-05-16 9:53 ` Joseph Lo
2013-05-16 18:19 ` Stephen Warren
2013-05-17 10:15 ` Joseph Lo
2013-05-17 10:27 ` Russell King - ARM Linux
2013-05-17 10:23 ` Russell King - ARM Linux
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