Re: [PATCH] of: use hash based search in of_find_node_by_phandle

From: Frank Rowand
Date: Fri Jan 26 2018 - 16:27:10 EST


On 01/26/18 00:22, Chintan Pandya wrote:
>
>
> On 1/26/2018 1:24 AM, Frank Rowand wrote:
>> On 01/25/18 02:14, Chintan Pandya wrote:
>>> of_find_node_by_phandle() takes a lot of time finding
>>> right node when your intended device is too right-side
>>> in the fdt. Reason is, we search each device serially
>>> from the fdt, starting from left-most to right-most.
>> Please give me a pointer to the code that is doing
>> this search.
>>
>> -Frank
> You can refer include/linux/of.h
>
> #define for_each_of_allnodes_from(from, dn) \
> ÂÂÂÂÂÂÂ for (dn = __of_find_all_nodes(from); dn; dn = __of_find_all_nodes(dn))
> #define for_each_of_allnodes(dn) for_each_of_allnodes_from(NULL, dn)
>
> where __of_find_all_nodes() does
>
> struct device_node *__of_find_all_nodes(struct device_node *prev)
> {
> ÂÂÂÂÂÂÂ struct device_node *np;
> ÂÂÂÂÂÂÂ if (!prev) {
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ np = of_root;
> ÂÂÂÂÂÂÂ } else if (prev->child) {
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ np = prev->child;
> ÂÂÂÂÂÂÂ } else {
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ /* Walk back up looking for a sibling, or the end of the structure */
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ np = prev;
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ while (np->parent && !np->sibling)
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ np = np->parent;
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ np = np->sibling; /* Might be null at the end of the tree */
> ÂÂÂÂÂÂÂ }
> ÂÂÂÂÂÂÂ return np;
> }
>

Let me restate my question.

Can you point me to the driver code that is invoking
the search?

-Frank