Messages in this thread | | | Date | Mon, 2 Nov 2015 13:12:55 -0800 | From | Brian Norris <> | Subject | Re: [PATCH v2 01/11] mtd: add get/set of_node/flash_node helpers |
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On Mon, Nov 02, 2015 at 12:27:58AM +0100, Boris Brezillon wrote: > On Fri, 30 Oct 2015 20:33:20 -0700 > Brian Norris <computersforpeace@gmail.com> wrote: > > > We are going to begin using the mtd->dev.of_node field for MTD device > > nodes, so let's add helpers for it. Also, we'll be making some > > conversions on spi_nor (and nand_chip eventually) too, so get that ready > > with their own helpers. > > > > Signed-off-by: Brian Norris <computersforpeace@gmail.com> > > --- > > v2: new > > > > include/linux/mtd/mtd.h | 11 +++++++++++ > > include/linux/mtd/nand.h | 11 +++++++++++ > > include/linux/mtd/spi-nor.h | 11 +++++++++++ > > 3 files changed, 33 insertions(+) > > > > diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h > > index f17fa75809aa..cc84923011c0 100644 > > --- a/include/linux/mtd/mtd.h > > +++ b/include/linux/mtd/mtd.h > > @@ -254,6 +254,17 @@ struct mtd_info { > > int usecount; > > }; > > > > +static inline void mtd_set_of_node(struct mtd_info *mtd, > > + struct device_node *np) > > +{ > > + mtd->dev.of_node = np; > > Maybe we should retain a reference to the device_node here (IOW, > replace '= np' by '= of_node_get(np)'). Of course this implies calling > of_node_put() when the mtd device is unregistered.
I'll admit I never really followed (nor verified) the OF get/put logic that well. But I suppose that makes sense.
> > +} > > + > > +static inline struct device_node *mtd_get_of_node(struct mtd_info *mtd) > > +{ > > + return mtd->dev.of_node; > > Not sure this is relevant to to the same here before returning the > device_node because it's mostly used by the MTD drivers and those are > the ones who called mtd_set_of_node() in the first place, so we can > assume it's safe to return an non-retained reference to a device_node.
I think once the node has been "set", its consumers should stay in sync with the lifetime of the MTD; so I think just that initial refcount is sufficient.
IOW, if MTD drivers are still fiddling with an MTD's of_node after the MTD is unregistered, then we've failed somewhere else.
Brian
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