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

[Frank Rowand]

On 01/26/18 13:27, Frank Rowand wrote:
> 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
> 

And also the .dts devicetree source file that you are seeing
large overhead with.