linux-kernel - Re: [PATCH v3 5/6] usb: chipidea: let chipidea core device of_node equal's glue layer device of

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Message-ID: <20160721101239.GB22749@shlinux2>
Date:	Thu, 21 Jul 2016 18:12:39 +0800
From:	Peter Chen <hzpeterchen@...il.com>
To:	Russell King - ARM Linux <linux@...linux.org.uk>
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, dwmw2@...radead.org,
	mark.rutland@....com, devicetree@...r.kernel.org,
	k.kozlowski@...sung.com, stephen.boyd@...aro.org,
	oscar@...andei.net, arnd@...db.de, pawel.moll@....com,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	s.hauer@...gutronix.de, linux-usb@...r.kernel.org,
	mail@...iej.szmigiero.name, troy.kisky@...ndarydevices.com,
	stillcompiling@...il.com, Peter Chen <peter.chen@...escale.com>,
	p.zabel@...gutronix.de, festevam@...il.com,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 5/6] usb: chipidea: let chipidea core device of_node
 equal's glue layer device of_node

On Thu, Jul 21, 2016 at 10:41:28AM +0100, Russell King - ARM Linux wrote:
> On Thu, Jul 21, 2016 at 05:20:12PM +0800, Peter Chen wrote:
> > On Thu, Jul 21, 2016 at 10:14:38AM +0100, Russell King - ARM Linux wrote:
> > > On Wed, Jul 20, 2016 at 05:40:28PM +0800, Peter Chen wrote:
> > > > diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
> > > > index 69426e6..0d05812 100644
> > > > --- a/drivers/usb/chipidea/core.c
> > > > +++ b/drivers/usb/chipidea/core.c
> > > > @@ -914,6 +914,16 @@ static int ci_hdrc_probe(struct platform_device *pdev)
> > > >  	if (!ci)
> > > >  		return -ENOMEM;
> > > >  
> > > > +	/*
> > > > +	 * 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;
> > > 
> > > This is a dangerous thing to do.  You're changing the dev->of_node of
> > > _this_ device, which means that _this_ driver will no longer match
> > > the device if you remove and reinsert the driver module, or unbind
> > > and try to re-bind the device to this driver.
> > > 
> > 
> > Thanks for commenting it.
> > 
> > I have tested load/unload, it does not show any problems.
> > 
> > The chipidea core device is created by code at runtime, not by device node.
> > And we have NO device node for this chipidea core device at dts.
> 
> Okay, so we still probably have the bind/unbind problem, where "dev"
> can be matched by the driver which claimed "dev->parent".  Remember,
> in an OF environment, driver matching is done by the compatible
> property, which is accessed via dev->of_node.
> 
> Therefore, I would suggest that you NULL dev->of_node in the error
> cleanup paths and in the remove function, so you don't have an
> unbound device with a duplicated (but inappropriate) dev->of_node
> pointer.
> 

Although it does no mismatch between driver and device due to the driver
has no of_match_table, I find it has below re-request pinctrl error
after re-bind, that's due to the parent device which has of_node
and there is a pinctrl property in it.

imx6sx-pinctrl 20e0000.iomuxc: pin MX6SX_PAD_GPIO1_IO10 already requested by 2184000.usb;
cannot claim for ci_hdrc.0

After adding your suggestion, this error has gone, thanks.


-- 

Best Regards,
Peter Chen