On 03/07/2018 02:21 PM, Rob Herring wrote:
> On Wed, Mar 7, 2018 at 4:14 PM, Tyrel Datwyler
> <tyreld@xxxxxxxxxxxxxxxxxx> wrote:
>> On 03/07/2018 12:38 PM, Rob Herring wrote:
>>> On Fri, Mar 02, 2018 at 08:46:44PM -0500, Tyrel Datwyler wrote:
>>>> There are a couple places in drivers/of where the root node is found
>>>> with a of_find_node_by_path("/") call. This call just returns
>>>> of_node_get(of_root) when the the path "/" is passed as a parameter.
>>>> So, lets fixup these instances to just do that instead.
>>>>
>>>> Signed-off-by: Tyrel Datwyler <tyreld@xxxxxxxxxxxxxxxxxx>
>>>> ---
>>>> drivers/of/base.c | 2 +-
>>>> drivers/of/platform.c | 4 ++--
>>>> 2 files changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>>>> index ad28de9..94c1b4d 100644
>>>> --- a/drivers/of/base.c
>>>> +++ b/drivers/of/base.c
>>>> @@ -455,7 +455,7 @@ int of_machine_is_compatible(const char *compat)
>>>> struct device_node *root;
>>>> int rc = 0;
>>>>
>>>> - root = of_find_node_by_path("/");
>>>> + root = of_node_get(of_root);
>>>
>>> The former seems more readable to me. I'll wait and see if Frank has any
>>> comments on this change.
>>
>> Fair enough. I find them equally readable now that we have a well named/defined global, namely "of_root", pointing at the device tree root. My primary goal was saving a function call, but I wasn't sure if anybody really cares enough. A quick check shows ~77 uses of "of_find_node_by_path("/")" in the kernel. Figured I'd start here and see what the consensus was.
>
> As far as outside drivers/of/ is concerned, we certainly don't want to
> expose global variables. But for most uses, you shouldn't need the
> root node pointer because most iterating or searching functions treat
> NULL as root.
In the majority of cases I've seen code searching or iterating that wants to start at root just passes NULL. So, agreed. I was more looking at cases where code actually wants the root node for looking up properties of root. Part of my misguidance is likely due to "of_root" being an exported symbol.
-Tyrel
>
> Rob
>
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