lkml.org 
[lkml]   [2016]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RESEND PATCH v2 7/7] usb: xhci: plat: add vbus regulator control
On Wed, Apr 27, 2016 at 06:25:16PM +0800, Jisheng Zhang wrote:
> On Wed, 27 Apr 2016 10:57:39 +0100 Mark Brown wrote:
> > On Wed, Apr 27, 2016 at 08:37:20AM +0300, Felipe Balbi wrote:

> > > > + vbus = devm_regulator_get(&pdev->dev, "vbus");

> > > devm_regulator_get_optional() ??

> > Does USB work without a VBUS? Unless the answer is yes then I'd expect
> > this to be just a normal regulator_get().

> Per spec no. But the vbus may be transparent to SW on some platforms, so I
> think devm_regulator_get_optional() is better.

Really, no. If it's physically there the software needs to be written
as such. Please see the documentation and list archives for extensive
discussion on this topic.

> > This is all completely broken unless the supply is optional.

> The supply is optional.

To repeat a supply is only optional if it might be physically absent.
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2016-04-27 15:41    [W:0.073 / U:0.360 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site