lkml.org 
[lkml]   [2020]   [Sep]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC 09/10] misc: hisi_hikey_usb: add support for Hikey 970
On Fri, Sep 04, 2020 at 02:38:48PM +0200, Mauro Carvalho Chehab wrote:
> Em Fri, 4 Sep 2020 13:23:03 +0100
> Mark Brown <broonie@kernel.org> escreveu:
>
> > On Fri, Sep 04, 2020 at 12:23:31PM +0200, Mauro Carvalho Chehab wrote:
> >
> > > + regulator = devm_regulator_get_optional(&pdev->dev, "hub-vdd");
> > > + if (IS_ERR(regulator)) {
> > > + if (PTR_ERR(regulator) == -EPROBE_DEFER) {
> > > + dev_info(&pdev->dev,
> > > + "waiting for hub-vdd-supply to be probed\n");
> > > + return PTR_ERR(regulator);
> > > + }
> > > +
> > > + /* let it fall back to regulator dummy */
> > > + regulator = devm_regulator_get(&pdev->dev, "hub-vdd");
> > > + if (IS_ERR(regulator)) {
> > > + dev_err(&pdev->dev,
> > > + "get hub-vdd-supply failed with error %ld\n",
> > > + PTR_ERR(regulator));
> > > + return PTR_ERR(regulator);
> > > + }
> > > + }

> > This seems weird - if the supply is non-optional why is the code trying
> > with devm_regulator_get_optional()? Just use normal get directly.

> That's meant to avoid problems with EPROBE_DEFER.

Which problems and in what way does it avoid them?

> See, Hikey 970 need to initialize 4 drivers for the regulators:
> SPMI core, SPMI bus controller, MFD and regulator. This can take
> some time. So, a first call to *regulator_get() may return
> EPROBE_DEFER, specially if both regulator drivers and USB HUB
> are builtin.

This is totally normal and works fine with normal regulator_get().

> I ended doing the same as some other DRM drivers do (like adv7535).

I can't find any references to regulator_get_optional()
drivers/gpu/drm/bridge/adv7511/adv7511_drv.c?
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2020-09-04 14:47    [W:1.363 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site