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SubjectRe: [PATCH] OF: base: match each node compatible against all given matches first
On 12/02/2013 06:03 AM, Thierry Reding wrote:
> On Thu, Nov 28, 2013 at 07:36:25PM +0100, Sebastian Hesselbarth
> 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 modifies of_match_node to match each of
>> the node's compatible strings against all given matches 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.
>>
>> Signed-off-by: Sebastian Hesselbarth
>> <sebastian.hesselbarth@gmail.com> --- Cc: Grant Likely
>> <grant.likely@linaro.org> Cc: Rob Herring
>> <rob.herring@calxeda.com> Cc: Benjamin Herrenschmidt
>> <benh@kernel.crashing.org> Cc: Russell King
>> <linux@arm.linux.org.uk> Cc: devicetree@vger.kernel.org Cc:
>> linux-arm-kernel@lists.infradead.org Cc:
>> linux-kernel@vger.kernel.org --- drivers/of/base.c | 47
>> ++++++++++++++++++++++++++++++++--------------- 1 file changed,
>> 32 insertions(+), 15 deletions(-)
>
> Hi Sebastian,
>
> I think you're one in a long line of people attempting to fix
> this. I tried myself over a year ago (commit 107a84e61cdd 'of:
> match by compatible property first') but it caused a subtle
> regression late in the release cycle and was reverted (commit
> bc51b0c22ceb 'Revert "of: match by compatible property first").
>
> Only recently there was another attempt [0] but it's pretty much
> equivalent to what I did back then.
>
> That said, I think you might actually have nailed it with this
> patch. From what I remember all earlier attempt failed because
> they didn't match all compatible/name/type combinations properly.
> I'm adding a few people on Cc who were involved with the other
> patches, perhaps they can give your patch a spin and see if it
> fixes things for them.

I agree and the change here is simple enough I think the chances of a
regression are low. But there is one issue...

>
> Thierry
>
> [0]: https://lkml.org/lkml/2013/10/3/585
>
>> diff --git a/drivers/of/base.c b/drivers/of/base.c index
>> 7d4c70f..183a9c7 100644 --- a/drivers/of/base.c +++
>> b/drivers/of/base.c @@ -713,23 +713,37 @@ static const struct
>> of_device_id *__of_match_node(const struct of_device_id *matches,
>> const struct device_node *node) { + const char *cp; + int cplen,
>> l; + if (!matches) return NULL;
>>
>> - while (matches->name[0] || matches->type[0] ||
>> matches->compatible[0]) { - int match = 1; - if
>> (matches->name[0]) - match &= node->name - &&
>> !strcmp(matches->name, node->name); - if (matches->type[0]) -
>> match &= node->type - && !strcmp(matches->type, node->type);
>> - if (matches->compatible[0]) - match &=
>> __of_device_is_compatible(node, - matches->compatible);
>> - if (match) - return matches; - matches++; + cp =
>> __of_get_property(node, "compatible", &cplen); + if (!cp) +
>> return NULL;

No compatible property and matching on name and/or type only is valid.
Remove the if here and changing the following should work:

>> + + while (cplen > 0) {

do {

>> + const struct of_device_id *m = matches; + + while
>> (m->name[0] || m->type[0] || m->compatible[0]) { + int match =
>> 1; + if (m->name[0]) + match &= node->name + &&
>> !strcmp(m->name, node->name); + if (m->type[0]) + match &=
>> node->type + && !strcmp(m->type, node->type); + if
>> (m->compatible[0])

if (cp && m->compatible[0])

>> + match &= !of_compat_cmp(cp, m->compatible, +
>> strlen(m->compatible)); + if (match) + return m; + m++; +
>> } + l = strlen(cp) + 1; + cp += l; + cplen -= l; }


} while (cp && (cplen > 0));


>> return NULL; } @@ -739,7 +753,10 @@ 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. Matching order + * is to compare each
>> of the node's compatibles with all given matches + * first. This
>> implies node's compatible is sorted from specific to + * generic
>> while matches can be in any order. */ const struct of_device_id
>> *of_match_node(const struct of_device_id *matches, const struct
>> device_node *node) -- 1.7.10.4
>>
>>
>> _______________________________________________ linux-arm-kernel
>> mailing list linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel



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