From mboxrd@z Thu Jan  1 00:00:00 1970
From: swarren@wwwdotorg.org (Stephen Warren)
Date: Wed, 22 May 2013 15:18:54 -0600
Subject: [PATCH] ARM: tegra: add cpu_disable for hotplug
In-Reply-To: <20130522090304.GT21944@tbergstrom-lnx.Nvidia.com>
References: <1369131215-2920-1-git-send-email-josephl@nvidia.com>
 <519B9DB4.7070106@wwwdotorg.org>
 <20130522090304.GT21944@tbergstrom-lnx.Nvidia.com>
Message-ID: <519D363E.4000409@wwwdotorg.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 05/22/2013 03:03 AM, Peter De Schrijver wrote:
> On Tue, May 21, 2013 at 06:15:48PM +0200, Stephen Warren wrote:
>> On 05/21/2013 04:13 AM, Joseph Lo wrote:
>>> The Tegra114 could hotplug the CPU0, but the common cpu_disable didn't
>>> support that. Adding a Tegra specific cpu_disable function for it.
>>>
>>> Signed-off-by: Joseph Lo <josephl@nvidia.com>
>>
>>> diff --git a/arch/arm/mach-tegra/hotplug.c b/arch/arm/mach-tegra/hotplug.c
>>
>>> +int tegra_cpu_disable(unsigned int cpu)
>>> +{
>>> +	switch (tegra_chip_id) {
>>> +	case TEGRA114:
>>> +		return 0;
>>> +	default:
>>> +		return cpu == 0 ? -EPERM : 0;
>>> +	}
>>> +}
>>
>> Do we expect all/most future chips to support hotplug of CPU0? Or at
>> least, fewer chips to have the restriction than not? If so, it might be
> 
> Yes. I think we can safely assume future chips will support hotplugging CPU0.
> 
>> more forward-looking to write that as:
>>
>> if (tegra_chip_id == TEGRA30)
>>     return cpu == 0 ? -EPERM : 0;
>>
> 
> Also Tegra20 doesn't support hotplugging CPU0?

Oh right, this isn't a Tegra30+ file. How about just inverting the
switch so it doesn't need to change later:

	switch (tegra_chip_id) {
	case TEGRA20:
	case TEGRA30:
		return cpu == 0 ? -EPERM : 0;
	default:
		return 0;
	}