From: Felipe Balbi <balbi@kernel.org>
To: Roger Quadros <rogerq@ti.com>, Stefan Agner <stefan@agner.ch>,
Mark Brown <broonie@kernel.org>
Cc: 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: Wed, 07 Sep 2016 11:03:19 +0300 [thread overview]
Message-ID: <87shtckugo.fsf@linux.intel.com> (raw)
In-Reply-To: <32e64ab2-2ed6-e177-b1ec-bce9e1eaa4b6@ti.com>
[-- Attachment #1: Type: text/plain, Size: 1748 bytes --]
Hi,
Roger Quadros <rogerq@ti.com> writes:
>>>> 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.
>>
>
> I think the right behaviour would be that if vcc-supply is specified
> in the DT then failure to get that supply is a serious failure and
> probe should fail.
>
> So the correct fix would be to call devm_regulator_get() only if
> needs_vcc is true.
The way it is, AFAICT, regulator fwk will return a dummy regulator for
cases where supply isn't in DT.
--
balbi
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 800 bytes --]
next prev parent reply other threads:[~2016-09-07 8:04 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
2016-09-07 7:25 ` Roger Quadros
2016-09-07 8:03 ` Felipe Balbi [this message]
2016-09-07 18:53 ` Mark Brown
2016-09-07 20:32 ` Stefan Agner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87shtckugo.fsf@linux.intel.com \
--to=balbi@kernel.org \
--cc=broonie@kernel.org \
--cc=fabio.estevam@nxp.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=rogerq@ti.com \
--cc=stefan@agner.ch \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).