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From:   Felipe Balbi <balbi@kernel.org>
To:     Mike Looijmans <mike.looijmans@topic.nl>,
        Mark Brown <broonie@kernel.org>
Cc:     Vincent Whitchurch <vincent.whitchurch@axis.com>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        gregkh@linuxfoundation.org, lgirdwood@gmail.com
Subject: Re: [PATCH v3] usb: dwc3: Add support for VBUS power control
In-Reply-To: <be4013b6-01c6-7f67-35ad-5c398b85c066@topic.nl>
References: <20200619142512.19824-1-mike.looijmans@topic.nl>
 <20200723075612.tn5dbkhes2chohwh@axis.com>
 <20200723110523.GA4759@sirena.org.uk>
 <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.2698920d-90ba-4c46-abda-83e18e2093c8@emailsignatures365.codetwo.com>
 <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.0d2bd5fa-15cc-4b27-b94e-83614f9e5b38.ac9c2a67-d7df-4f70-81b3-db983bbfb4db@emailsignatures365.codetwo.com>
 <e63ee918-c9e3-a8ee-e7c5-577b5a3e09be@topic.nl>
 <20200727102317.GA6275@sirena.org.uk>
 <be4013b6-01c6-7f67-35ad-5c398b85c066@topic.nl>
Date:   Mon, 07 Sep 2020 10:44:55 +0300
Message-ID: <87a6y21154.fsf@kernel.org>
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Hi,

Mike Looijmans <mike.looijmans@topic.nl> writes:
> Met vriendelijke groet / kind regards,
>
> Mike Looijmans
> System Expert
>
>
> TOPIC Embedded Products B.V.
> Materiaalweg 4, 5681 RJ Best
> The Netherlands
>
> T: +31 (0) 499 33 69 69
> E: mike.looijmans@topicproducts.com
> W: www.topicproducts.com
>
> Please consider the environment before printing this e-mail
> On 27-07-2020 12:23, Mark Brown wrote:
>> On Sun, Jul 26, 2020 at 09:10:39AM +0200, Mike Looijmans wrote:
>>> On 23-07-2020 13:05, Mark Brown wrote:
>>=20
>>>> Does the device actually support running without power so that's a thi=
ng
>>>> that can happen?  _get_optional() should only ever be used for supplies
>>>> that may be physically absent.
>>=20
>>> It's the 5V VBUS power for the USB "plug" that's being controlled here.=
 It
>>> must turned on when the controller is in "host" mode. Some boards arran=
ge
>>> this in hardware through the PHY, and some just don't have any control =
at
>>> all and have it permanently on or off. On a board where the 5V is contr=
olled
>>> using a GPIO line or an I2C chip, this patch is required to make it wor=
k.
>>=20
>> That sounds like the driver should not be using _get_optional() then.
>>=20
>
> Making it mandatory would break most (read: all except Topic's) existing=
=20
> boards as they won't have it in their devicetree. I'm perfectly okay with=
=20
> that, but others might disagree.

you're perfectly okay with break all existing users of the driver?
That's a bit harsh

=2D-=20
balbi

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