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Subject: Re: [PATCH v3] usb: dwc3: Add support for VBUS power control
To:     Mark Brown <broonie@kernel.org>
CC:     Vincent Whitchurch <vincent.whitchurch@axis.com>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        balbi@kernel.org, gregkh@linuxfoundation.org, lgirdwood@gmail.com
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From:   Mike Looijmans <mike.looijmans@topic.nl>
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Met vriendelijke groet / kind regards,=0A=
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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 thin=
g
>>> 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 arrang=
e
>> this in hardware through the PHY, and some just don't have any control a=
t
>> all and have it permanently on or off. On a board where the 5V is contro=
lled
>> using a GPIO line or an I2C chip, this patch is required to make it work=
.
>=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.