From: Stefan Agner <stefan@agner.ch>
To: Mark Brown <broonie@kernel.org>
Cc: Felipe Balbi <balbi@kernel.org>,
gregkh@linuxfoundation.org, fabio.estevam@nxp.com,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb: phy: generic: request regulator optionally
Date: Tue, 06 Sep 2016 11:01:15 -0700 [thread overview]
Message-ID: <56840b0a8520f348ee0517390f518274@agner.ch> (raw)
In-Reply-To: <20160906082210.GE3950@sirena.org.uk>
On 2016-09-06 01:22, Mark Brown wrote:
> On Tue, Sep 06, 2016 at 10:45:19AM +0300, Felipe Balbi wrote:
>> Stefan Agner <stefan@agner.ch> writes:
>
>> > According to the device tree bindings the vcc-supply is optional.
>
> This is nonsense unless the device can work without this supply. Given
> that the supply is called VCC that doesn't seem entirely likely.
Afaik it is kind of a generic device tree binding, I guess the physical
device can have various appearances and properties...
A quick survey showed several device trees which do not specify
vcc-supply...
That said, I checked the device at hand, and it actually has a USB PHY
power supply inputs, but the device tree does not model them.
>> > + nop->vcc = devm_regulator_get_optional(dev, "vcc");
>> > if (IS_ERR(nop->vcc)) {
>> > dev_dbg(dev, "Error getting vcc regulator: %ld\n",
>> > PTR_ERR(nop->vcc));
>> > - if (needs_vcc)
>> > - return -EPROBE_DEFER;
>> > + if (needs_vcc || PTR_ERR(nop->vcc) == -EPROBE_DEFER)
>> > + return PTR_ERR(nop->vcc);
>
>> does this look okay from a regulator API perspective?
>
> That's how to use _get_optional() but it's really unusual that you
> should be using _get_optional().
Despite the above findings, I still think it is the right thing to do as
long as we specify vcc-supply to be optional.
--
Stefan
next prev parent reply other threads:[~2016-09-06 18:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-04 4:04 [PATCH] usb: phy: generic: request regulator optionally Stefan Agner
2016-09-06 7:45 ` Felipe Balbi
2016-09-06 8:22 ` Mark Brown
2016-09-06 18:01 ` Stefan Agner [this message]
2016-09-07 7:25 ` Roger Quadros
2016-09-07 8:03 ` Felipe Balbi
2016-09-07 18:53 ` Mark Brown
2016-09-07 20:32 ` Stefan Agner
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