On Fri, 14 Feb 2014 13:22:46 +0800, Kevin Hao <haokexin@xxxxxxxxx> 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@xxxxxxxxx>
> Signed-off-by: Kevin Hao <haokexin@xxxxxxxxx>
> ---
> 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++;
This seems wrong also. The compatible order should be checked for even
when m->name or m->type are set. You actually need to score the entries
to do this properly. The pseudo-code should look like this:
uint best_score = ~0;
of_device_id *best_match = NULL;
for_each(matches) {
uint score = ~0;
for_each_compatible(index) {
if (match->compatible == compatible[index])
score = index * 10;
}
/* Matching name is a bit better than not */
if (match->name == node->name)
score--;
/* Matching type is better than matching name */
/* (but matching both is even better than that */
if (match->type == node->type)
score -= 2;
if (score < best_score)
best_match = match;
}
return best_match;
This is actually very similar to the original code. It is an easy
modification. This is very similar to how the of_fdt_is_compatible()
function works.
g.
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