linux-kernel - Re: [PATCH] of: use hash based search in of_find_node_by

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Date:   Fri, 26 Jan 2018 13:52:15 +0530
From:   Chintan Pandya <cpandya@...eaurora.org>
To:     Frank Rowand <frowand.list@...il.com>, robh+dt@...nel.org,
        devicetree@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] of: use hash based search in of_find_node_by_phandle



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) \
         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)
{
         struct device_node *np;
         if (!prev) {
                 np = of_root;
         } else if (prev->child) {
                 np = prev->child;
         } else {
                 /* Walk back up looking for a sibling, or the end of 
the structure */
                 np = prev;
                 while (np->parent && !np->sibling)
                         np = np->parent;
                 np = np->sibling; /* Might be null at the end of the 
tree */
         }
         return np;
}

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