[PATCH 2/2] of: search the best compatible match first in __of_match_node()

[Kumar Gala]

On Feb 14, 2014, at 9:53 AM, Rob Herring <robherring2 at gmail.com> wrote:

> On Thu, Feb 13, 2014 at 11:22 PM, Kevin Hao <haokexin at gmail.com> wrote:
>> Currently, of_match_node compares each given match against all node's
>> compatible strings with of_device_is_compatible.
>> 
>> To achieve multiple compatible strings per node with ordering from
>> specific to generic, this requires given matches to be ordered from
>> specific to generic. For most of the drivers this is not true and also
>> an alphabetical ordering is more sane there.
>> 
>> Therefore, this patch introduces a function to match each of the node's
>> compatible strings against all given compatible matches without type and
>> name first, before checking the next compatible string. This implies
>> that node's compatibles are ordered from specific to generic while
>> given matches can be in any order. If we fail to find such a match
>> entry, then fall-back to the old method in order to keep compatibility.
>> 
>> Cc: Sebastian Hesselbarth <sebastian.hesselbarth at gmail.com>
>> Signed-off-by: Kevin Hao <haokexin at gmail.com>
> 
> Looks good to me. I'll put this in next for a few days. I'd really
> like to see some acks and tested-by's before sending to Linus.
> 
> We could be a bit more strict here and fallback to the old matching if
> the match table has any entries with name or type. I don't think that
> should be necessary though.
> 
> Rob

Can you push the revert to Linus sooner, since currently a ton of boards wouldn’t be working on the PPC side, so at least -rc3 has the possibility of working for them.

- k

> 
>> ---
>> drivers/of/base.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 42 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>> index ba195fbce4c6..10b51106c854 100644
>> --- a/drivers/of/base.c
>> +++ b/drivers/of/base.c
>> @@ -730,13 +730,49 @@ out:
>> }
>> EXPORT_SYMBOL(of_find_node_with_property);
>> 
>> +static const struct of_device_id *
>> +of_match_compatible(const struct of_device_id *matches,
>> +                       const struct device_node *node)
>> +{
>> +       const char *cp;
>> +       int cplen, l;
>> +       const struct of_device_id *m;
>> +
>> +       cp = __of_get_property(node, "compatible", &cplen);
>> +       while (cp && (cplen > 0)) {
>> +               m = matches;
>> +               while (m->name[0] || m->type[0] || m->compatible[0]) {
>> +                       /* Only match for the entries without type and name */
>> +                       if (m->name[0] || m->type[0] ||
>> +                               of_compat_cmp(m->compatible, cp,
>> +                                        strlen(m->compatible)))
>> +                               m++;
>> +                       else
>> +                               return m;
>> +               }
>> +
>> +               /* Get node's next compatible string */
>> +               l = strlen(cp) + 1;
>> +               cp += l;
>> +               cplen -= l;
>> +       }
>> +
>> +       return NULL;
>> +}
>> +
>> static
>> const struct of_device_id *__of_match_node(const struct of_device_id *matches,
>>                                           const struct device_node *node)
>> {
>> +       const struct of_device_id *m;
>> +
>>        if (!matches)
>>                return NULL;
>> 
>> +       m = of_match_compatible(matches, node);
>> +       if (m)
>> +               return m;
>> +
>>        while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
>>                int match = 1;
>>                if (matches->name[0])
>> @@ -760,7 +796,12 @@ const struct of_device_id *__of_match_node(const struct of_device_id *matches,
>>  *     @matches:       array of of device match structures to search in
>>  *     @node:          the of device structure to match against
>>  *
>> - *     Low level utility function used by device matching.
>> + *     Low level utility function used by device matching. We have two ways
>> + *     of matching:
>> + *     - Try to find the best compatible match by comparing each compatible
>> + *       string of device node with all the given matches respectively.
>> + *     - If the above method failed, then try to match the compatible by using
>> + *       __of_device_is_compatible() besides the match in type and name.
>>  */
>> const struct of_device_id *of_match_node(const struct of_device_id *matches,
>>                                         const struct device_node *node)
>> --
>> 1.8.5.3

-- 
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