Re: [PATCH v3 5/6] usb: chipidea: let chipidea core device of_node equal's glue layer device of_node
From: Russell King - ARM Linux
Date: Thu Jul 21 2016 - 05:42:09 EST
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
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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