From: Stephen Warren <swarren@wwwdotorg.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Wei Ni <wni@nvidia.com>, Mark Brown <broonie@kernel.org>,
"khali@linux-fr.org" <khali@linux-fr.org>,
"lm-sensors@lm-sensors.org" <lm-sensors@lm-sensors.org>,
"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/2] hwmon: (lm90) Add power control
Date: Mon, 09 Sep 2013 21:40:30 -0600 [thread overview]
Message-ID: <522E94AE.7000804@wwwdotorg.org> (raw)
In-Reply-To: <522E93D6.2010304@roeck-us.net>
On 09/09/2013 09:36 PM, Guenter Roeck wrote:
> On 09/09/2013 08:22 PM, Wei Ni wrote:
>> On 09/09/2013 11:50 PM, Guenter Roeck wrote:
>>> On Mon, Sep 09, 2013 at 02:50:22PM +0100, Mark Brown wrote:
>>>> On Mon, Sep 09, 2013 at 04:34:43AM -0700, Guenter Roeck wrote:
>>>>> On 09/09/2013 04:12 AM, Mark Brown wrote:
>>>>>> On Mon, Sep 09, 2013 at 06:29:11PM +0800, Wei Ni wrote:
>>>>
>>>>>> This doesn't look good, it is going to ignore actual errors - I
>>>>>> *really*
>>>>>> doubt that vcc is optional, it looks like it's the main power
>>>>>> supply for
>>>>>> the device. You should use normal regulator_get(), _optional() is
>>>>>> for
>>>>>> supplies which could physically not be provided in a system (eg,
>>>>>> if the
>>>>>> device can generate them internally if required).
>>>>
>>>>> Then he'll have to make sure that all devicetree files in the system
>>>>> contain references to this regulator.
>>>>
>>>> Or get the patches applied on top of the code that'll be going in this
>>>> cycle implementing get_optional() properly - when that's done the
>>>> default will be to provide a dummy supply for regulator_get(). If you
>>>> ack the patch I'd be happy to carry it.
>>>>
>>> Jean will have to ack it.
>>>
>> I think it's better to use get_optional(), and ignore the errors except
>> -EPROBE_DEFER. Because many platform may always power on this device,
>> and will not provide regulator for it, so if we get errors from
>> regulator subsystem and return it directly, then the probe() can't be
>> implemented, this driver can't work properly, even though it can work
>> without regulator support.
>> Mark, do you mean you have patches for regulator_get_optional() and
>> regulator_get()?
>>
>
> My understanding is that by adding regulator support you essentially
> committed to adding regulators (if necessary dummy ones) for this driver
> to all those platforms. This is quite similar to other drivers in the
> same situation. Once you start along that route, you'll have to go it
> all the way.
By using regulator_get_optional(), the regulator should be optional,
hence you only have to add it to platforms that need it.
next prev parent reply other threads:[~2013-09-10 3:40 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-09 10:29 [PATCH v3 0/2] Add power control for lm90 Wei Ni
2013-09-09 10:29 ` [PATCH v3 1/2] hwmon: (lm90) Add power control Wei Ni
2013-09-09 11:12 ` Mark Brown
2013-09-09 11:34 ` Guenter Roeck
2013-09-09 13:50 ` Mark Brown
2013-09-09 15:50 ` Guenter Roeck
2013-09-09 16:02 ` Mark Brown
2013-09-09 16:17 ` Guenter Roeck
2013-09-09 20:39 ` Mark Brown
2013-09-10 4:05 ` Wei Ni
2013-09-10 4:50 ` Guenter Roeck
2013-09-10 5:39 ` Wei Ni
2013-09-10 5:54 ` Guenter Roeck
2013-09-10 6:30 ` Wei Ni
2013-09-10 10:13 ` Mark Brown
2013-09-10 11:29 ` Wei Ni
2013-09-10 12:11 ` Mark Brown
2013-09-11 9:40 ` Wei Ni
2013-09-10 3:22 ` Wei Ni
2013-09-10 3:36 ` Guenter Roeck
2013-09-10 3:40 ` Stephen Warren [this message]
2013-09-10 3:53 ` Guenter Roeck
2013-09-10 4:12 ` Wei Ni
2013-09-10 4:13 ` Stephen Warren
2013-09-10 4:44 ` Guenter Roeck
2013-09-10 10:09 ` Mark Brown
2013-09-10 15:07 ` Stephen Warren
2013-09-10 17:04 ` Mark Brown
2013-09-10 17:44 ` Stephen Warren
2013-09-10 18:07 ` Guenter Roeck
2013-09-10 18:18 ` Mark Brown
2013-09-10 18:37 ` Stephen Warren
2013-09-10 18:52 ` Mark Brown
2013-09-11 11:35 ` Wei Ni
2013-09-10 17:05 ` Mark Brown
2013-09-09 10:29 ` [PATCH v3 2/2] Documentation: dt: hwmon: add OF document for LM90 Wei Ni
2013-09-09 10:52 ` Guenter Roeck
2013-09-09 22:14 ` Stephen Warren
2013-09-10 4:25 ` Wei Ni
2013-09-09 10:57 ` Ramkumar Ramachandra
2013-09-10 4:35 ` Wei Ni
2013-09-10 4:36 ` Wei Ni
2013-09-09 22:15 ` Stephen Warren
2013-09-09 22:23 ` Guenter Roeck
2013-09-10 4:25 ` Wei Ni
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