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    SubjectRE: [RFC PATCH v3 1/5] dt: add of_get_child_count helper function
    Hi,

    Dong Aisheng-B29396 writes:
    > > -----Original Message-----
    > > From: Marek Vasut [mailto:marek.vasut@gmail.com]
    > > Sent: Wednesday, December 21, 2011 3:47 AM
    > > To: linux-arm-kernel@lists.infradead.org
    > > Cc: Dong Aisheng-B29396; linux-kernel@vger.kernel.org;
    > > linus.walleij@stericsson.com; s.hauer@pengutronix.de; w.sang@pengutronix.de;
    > > rob.herring@calxeda.com; grant.likely@secretlab.ca; kernel@pengutronix.de;
    > > cjb@laptop.org; devicetree-discuss@lists.ozlabs.org; Guo Shawn-R65073
    > > Subject: Re: [RFC PATCH v3 1/5] dt: add of_get_child_count helper function
    > > Importance: High
    > >
    > > > From: Dong Aisheng <dong.aisheng@linaro.org>
    > > >
    > > > Currently most code to get child count in kernel are almost same, add
    > > > a helper to implement this function for dt to use.
    > > >
    > > > ---
    > > > Changes v1->v2:
    > > > * change the name from of_get_child_number to of_get_child_count
    > > >
    > > > Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
    > > > Cc: Grant Likely <grant.likely@secretlab.ca>
    > > > Cc: Rob Herring <rob.herring@calxeda.com>
    > > > ---
    > > > include/linux/of.h | 16 ++++++++++++++++
    > > > 1 files changed, 16 insertions(+), 0 deletions(-)
    > > >
    > > > diff --git a/include/linux/of.h b/include/linux/of.h index
    > > > 4948552..d0d91a1 100644
    > > > --- a/include/linux/of.h
    > > > +++ b/include/linux/of.h
    > > > @@ -189,6 +189,17 @@ extern struct device_node
    > > > *of_get_next_child(const struct device_node *node, for (child =
    > > > of_get_next_child(parent, NULL); child != NULL; \
    > > > child = of_get_next_child(parent, child))
    > > >
    > > > +static inline int of_get_child_count(const struct device_node *np) {
    > > > + struct device_node *child = NULL;
    > > > + int num = 0;
    > > > +
    > > > + while ((child = of_get_next_child(np, child)))
    > >
    > > The assignment in this condition really looks eerie, maybe just rewrite it to do
    > > { } while () ? Also, aren't the parenthesis unnecessary?
    > >
    > Yes, one more parenthesis. I will remove it. Thanks.
    > For the condition, it's a little trick but I guess for a helper function
    > it's ok right? And there're already many places using like this.
    >
    It's a bad habit to use an assignment as an expression. It always
    looks like someone used '=' instead of '=='.

    You should make it clear that that's not the case like:
    | while ((child = of_get_next_child(np, child)) != NULL)


    Lothar Waßmann
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