linux-kernel - Re: [PATCH v1 1/2] device property: Keep secondary firmware node secondary by type

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Message-ID: <20201023141932.GW4077@smile.fi.intel.com>
Date:   Fri, 23 Oct 2020 17:19:32 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Ferry Toth <fntoth@...il.com>
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        Saravana Kannan <saravanak@...gle.com>,
        linux-acpi@...r.kernel.org, "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH v1 1/2] device property: Keep secondary firmware node
 secondary by type

On Fri, Oct 23, 2020 at 04:03:20PM +0200, Ferry Toth wrote:
> Hi
> 
> Op 23-10-2020 om 14:34 schreef Heikki Krogerus:
> > On Thu, Oct 22, 2020 at 09:40:59PM +0300, Andy Shevchenko wrote:
> > > Behind primary and secondary we understand the type of the nodes
> > > which might define their ordering. However, if primary node gone,
> > > we can't maintain the ordering by definition of the linked list.
> > > Thus, by ordering secondary node becomes first in the list.
> > > But in this case the meaning of it is still secondary (or auxiliary).
> > > The type of the node is maintained by the secondary pointer in it:
> > > 
> > > 	secondary pointer		Meaning
> > > 	NULL or valid			primary node
> > > 	ERR_PTR(-ENODEV)		secondary node
> > > 
> > > So, if by some reason we do the following sequence of calls
> > > 
> > > 	set_primary_fwnode(dev, NULL);
> > > 	set_primary_fwnode(dev, primary);
> > > 
> > > we should preserve secondary node.
> > > 
> > > This concept is supported by the description of set_primary_fwnode()
> > > along with implementation of set_secondary_fwnode(). Hence, fix
> > > the commit c15e1bdda436 to follow this as well.
> > > 
> > > Fixes: c15e1bdda436 ("device property: Fix the secondary firmware node handling in set_primary_fwnode()")
> > > Cc: Ferry Toth <fntoth@...il.com>
> > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > FWIW:
> > 
> > Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > Tested-by: Ferry Toth <fntoth@...il.com>

The quoting above is broken, I dare to put it below without any quoting.

Tested-by: Ferry Toth <fntoth@...il.com>

> > > ---
> > >   drivers/base/core.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > > index c852f16c111b..41feab679fa1 100644
> > > --- a/drivers/base/core.c
> > > +++ b/drivers/base/core.c
> > > @@ -4278,7 +4278,7 @@ void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
> > >   	} else {
> > >   		if (fwnode_is_primary(fn)) {
> > >   			dev->fwnode = fn->secondary;
> > > -			fn->secondary = NULL;
> > > +			fn->secondary = ERR_PTR(-ENODEV);
> > >   		} else {
> > >   			dev->fwnode = NULL;
> > >   		}
> > > -- 
> > > 2.28.0

-- 
With Best Regards,
Andy Shevchenko