From: wni@nvidia•com (Wei Ni)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 1/3] hwmon: (lm90) Add power control
Date: Fri, 9 Aug 2013 15:23:31 +0800 [thread overview]
Message-ID: <520498F3.8030101@nvidia.com> (raw)
In-Reply-To: <20130808110136.GA6427@sirena.org.uk>
On 08/08/2013 07:01 PM, Mark Brown wrote:
> * PGP Signed by an unknown key
>
> On Thu, Aug 08, 2013 at 02:56:29PM +0800, Wei Ni wrote:
>
>> + mutex_lock(&data->update_lock);
>> +
>> + if (is_enable)
>> + ret = regulator_enable(data->lm90_reg);
>> + else
>> + ret = regulator_disable(data->lm90_reg);
>> +
>> + if (ret < 0)
>> + dev_err(&client->dev,
>> + "Error in %s rail vdd, error %d\n",
>> + (is_enable) ? "enabling" : "disabling", ret);
>> + else
>> + dev_info(&client->dev, "success in %s rail vdd\n",
>> + (is_enable) ? "enabling" : "disabling");
>> +
>> + mutex_unlock(&data->update_lock);
>
> Two things here. One is that it's not clear what this lokc is
> protecting since the only thing in the locked region is the regulator
> operation and that is thread safe. The other thing is that I'm not
> seeing anthing that ensures that enables and disables are matched -
> regulators are reference counted so two enables need two disables.
>
>> + data->lm90_reg = regulator_get(&client->dev, "vdd");
>> + if (IS_ERR_OR_NULL(data->lm90_reg)) {
>
> NULL is a valid regulator, use IS_ERR().
>
>> + if (PTR_ERR(data->lm90_reg) == -ENODEV)
>> + dev_info(&client->dev,
>> + "No regulator found for vdd. Assuming vdd is always powered.");
>> + else
>> + dev_warn(&client->dev,
>> + "Error [%ld] in getting the regulator handle for vdd.\n",
>> + PTR_ERR(data->lm90_reg));
>
> You shouldn't just be ignoring errors here, though there are deployment
> difficulties with making sure a stub regulator is provided. These
> should be getting easier after the next merge window, the stubs will be
> being tweaked slightly to have an "assume it's there" option even when
Oh, really, could you show me the patch, I wish to take a look :)
Wei.
> regulators are used. Especially in cases with device tree you should be
> paying attention to -EPROBE_DEFER, that will accurately reflect if a
> regulator is present but not loaded yet.
>
> That said if you *are* going to do this you should request the
> regulator using devm_regulator_get_optional(), this is intended to
> support things that don't need regulators (though that's not the case
> here).
>
> * Unknown Key
> * 0x7EA229BD
>
next prev parent reply other threads:[~2013-08-09 7:23 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-08 6:56 [PATCH v2 0/3] Add power control for lm90 Wei Ni
2013-08-08 6:56 ` [PATCH v2 1/3] hwmon: (lm90) Add power control Wei Ni
2013-08-08 7:13 ` Alexander Shiyan
2013-08-08 9:26 ` Wei Ni
2013-08-08 8:42 ` Guenter Roeck
2013-08-08 9:47 ` Wei Ni
2013-08-08 9:57 ` Alexander Shiyan
2013-08-08 9:59 ` Wei Ni
2013-08-08 10:07 ` Wei Ni
2013-08-08 11:23 ` Guenter Roeck
2013-08-08 17:33 ` Stephen Warren
2013-08-08 17:59 ` Guenter Roeck
2013-08-08 18:45 ` Stephen Warren
2013-08-08 17:30 ` Stephen Warren
2013-08-08 17:59 ` Guenter Roeck
2013-08-08 19:27 ` Mark Brown
2013-08-08 11:01 ` Mark Brown
2013-08-08 11:25 ` Guenter Roeck
2013-08-08 13:08 ` Mark Brown
2013-08-08 15:21 ` Guenter Roeck
2013-08-08 17:15 ` Mark Brown
2013-08-08 20:00 ` Guenter Roeck
2013-08-08 21:18 ` Mark Brown
2013-08-08 21:30 ` Guenter Roeck
[not found] ` <1376027820.695103970@f416.i.mail.ru>
2013-08-09 10:27 ` Proposal: I2C device power (Was: hwmon: (lm90) Add power control) Mark Brown
2013-08-09 10:50 ` Alexander Shiyan
2013-08-09 11:09 ` Mark Brown
2013-08-09 7:23 ` Wei Ni [this message]
2013-08-09 10:56 ` [PATCH v2 1/3] hwmon: (lm90) Add power control Mark Brown
2013-08-08 6:56 ` [PATCH v2 2/3] ARM: dt: t114 dalmore: add dt entry for nct1008 Wei Ni
2013-08-08 17:35 ` Stephen Warren
2013-08-09 6:06 ` Wei Ni
2013-08-08 20:36 ` Sergei Shtylyov
2013-08-08 20:40 ` Stephen Warren
2013-08-08 21:33 ` Guenter Roeck
2013-08-09 6:16 ` Wei Ni
2013-08-08 6:56 ` [PATCH v2 3/3] Documentation: dt: hwmon: add OF document for lm90 Wei Ni
2013-08-08 17:37 ` Stephen Warren
2013-08-09 6:10 ` Wei Ni
2013-08-09 16:35 ` Stephen Warren
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