linux-kernel - Re: [PATCH v5 5/6] usb: chipidea: let chipidea core device of_node equal's glue layer device of

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Date:	Wed, 10 Aug 2016 17:19:30 +0800
From:	Peter Chen <hzpeterchen@...il.com>
To:	Jun Li <jun.li@....com>
Cc:	Stephen Boyd <stephen.boyd@...aro.org>,
	Peter Chen <peter.chen@....com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
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	Peter Chen <peter.chen@...escale.com>
Subject: Re: [PATCH v5 5/6] usb: chipidea: let chipidea core device of_node
 equal's glue layer device of_node

On Wed, Aug 10, 2016 at 09:00:15AM +0000, Jun Li wrote:
> Hi, Peter
> 
> > -----Original Message-----
> > From: linux-usb-owner@...r.kernel.org [mailto:linux-usb-
> > owner@...r.kernel.org] On Behalf Of Peter Chen
> > Sent: Wednesday, August 10, 2016 11:12 AM
> > To: Stephen Boyd <stephen.boyd@...aro.org>
> > Cc: Peter Chen <peter.chen@....com>; gregkh@...uxfoundation.org;
> > stern@...land.harvard.edu; ulf.hansson@...aro.org; broonie@...nel.org;
> > sre@...nel.org; robh+dt@...nel.org; shawnguo@...nel.org;
> > dbaryshkov@...il.com; dwmw3@...radead.org; k.kozlowski@...sung.com; linux-
> > arm-kernel@...ts.infradead.org; p.zabel@...gutronix.de;
> > devicetree@...r.kernel.org; pawel.moll@....com; mark.rutland@....com;
> > linux-usb@...r.kernel.org; arnd@...db.de; s.hauer@...gutronix.de;
> > mail@...iej.szmigiero.name; troy.kisky@...ndarydevices.com;
> > festevam@...il.com; oscar@...andei.net; linux-pm@...r.kernel.org;
> > stillcompiling@...il.com; linux-kernel@...r.kernel.org; mka@...omium.org;
> > Peter Chen <peter.chen@...escale.com>
> > Subject: Re: [PATCH v5 5/6] usb: chipidea: let chipidea core device
> > of_node equal's glue layer device of_node
> > 
> > On Tue, Aug 09, 2016 at 05:15:36PM -0700, Stephen Boyd wrote:
> > > Quoting Peter Chen (2016-08-08 01:52:10)
> > > > From: Peter Chen <peter.chen@...escale.com>
> > > >
> > > > At device tree, we have no device node for chipidea core, the glue
> > > > layer's node is the parent node for host and udc device. But in
> > > > related driver, the parent device is chipidea core. So, in order to
> > > > let the common driver get parent's node, we let the core's device
> > > > node equals glue layer device node.
> > > >
> > > > Signed-off-by: Peter Chen <peter.chen@...escale.com>
> > > > Tested-by: Maciej S. Szmigiero <mail@...iej.szmigiero.name>
> > > > Tested-by Joshua Clayton <stillcompiling@...il.com>
> > > > ---
> > > >  drivers/usb/chipidea/core.c | 11 +++++++++++
> > > >  1 file changed, 11 insertions(+)
> > > >
> > > > diff --git a/drivers/usb/chipidea/core.c
> > > > b/drivers/usb/chipidea/core.c index 69426e6..b189dc7 100644
> > > > --- a/drivers/usb/chipidea/core.c
> > > > +++ b/drivers/usb/chipidea/core.c
> > > > @@ -954,6 +954,15 @@ static int ci_hdrc_probe(struct platform_device
> > *pdev)
> > > >                 dev_err(dev, "unable to init phy: %d\n", ret);
> > > >                 return ret;
> > > >         }
> > > > +       /*
> > > > +        * At device tree, we have no device node for chipidea core,
> > > > +        * the glue layer's node is the parent node for host and udc
> > > > +        * device. But in related driver, the parent device is
> > chipidea
> > > > +        * core. So, in order to let the common driver get parent's
> > node,
> > > > +        * we let the core's device node equals glue layer's node.
> > > > +        */
> > > > +       if (dev->parent && dev->parent->of_node)
> > > > +               dev->of_node = dev->parent->of_node;
> > >
> > > Can this be done earlier? Perhaps after hw_device_init() in this probe
> > > routine? That would allow me to remove the awkward parent searching in
> > > my ULPI DT awareness patch.
> > 
> > The reason why I locate it there is to avoid "goto label" for error path
> > during PHY's get and initialization operation.
> > 
> > Ok, to simplify your work, I will change it at next version.
> 
> As iommu need this to be done even more earlier, will you consider to
> put it before adding the core's platform device?
> 

I can't do it, it will introduce another issue that the pinctrl has
already requested by parents. The warning is similar like below, but
occurs at the probe.

http://lkml.iu.edu/hypermail/linux/kernel/1607.2/03150.html

I will see how iommu support can be added for platform devices which
are created by runtime (like chipidea core device).

-- 

Best Regards,
Peter Chen